North Korea for the first time showed images of the centrifuges that produce fuel for its nuclear bombs on Friday, as leader Kim Jong Un visited a uranium enrichment facility and called for more weapons-grade material to boost the arsenal.

The state media report on Kim's visit to the Nuclear Weapons Institute and a production base for weapon-grade nuclear materials was accompanied by the first photos of the centrifuges, providing a rare look inside North Korea's nuclear programme, which is banned under multiple United Nations Security Council resolutions, Reuters reported.

The photos showed Kim walking between long rows of metal centrifuges, the machines that enrich uranium. The report did not make clear when the visit occurred nor the facility's location.

Kim urged workers to produce more materials for tactical nuclear weapons, saying the country's nuclear arsenal is vital for confronting threats from the United States and its allies.

The weapons are needed for "self-defence and the capability for a preemptive attack," he said.

The North Korean leader said "anti-DPRK nuclear threats" from the "U.S. imperialists-led vassal forces" have crossed the red-line, according to the report.

South Korea condemned North Korea's unveiling of its uranium enrichment facility and will never accept Pyongyang's possession of nuclear weapons, the South's unification ministry said.

North Korea is believed to have several sites for enriching uranium. Analysts say commercial satellite imagery has shown construction in recent years at the main Yongbyon Nuclear Scientific Research Center, including its uranium enrichment plant, suggesting possible expansion.

Uranium is a radioactive element that exists naturally. To make nuclear fuel, raw uranium undergoes processes that result in a material with an increased concentration of the isotope uranium-235.

International Atomic Energy Agency chief Rafael Grossi said on Monday that the U.N. nuclear watchdog had observed activity consistent with the operation of a reactor and the reported centrifuge enrichment facility at Yongbyon.

NEW CENTRIFUGES

Kim stressed the need to boost the number of centrifuges so as to "exponentially increase" North Korea's nuclear arsenal, and expand the use of a new type of centrifuge to strengthen the production of weapon-grade nuclear materials.

The centrifuges seen in the photos appear smaller and shorter than the types previously believed to be used by North Korea, suggesting it had developed its own centrifuges to enhance separation capabilities, said Lee Sang-kyu, a nuclear engineering expert at South Korea's Korea Institute for Defense Analysis.

The photos also confirmed that the North is using a cascade system where large numbers of centrifuges are interconnected to achieve highly enriched uranium, he added.

The new type of centrifuge shows North Korea is advancing its fuel cycle capabilities, said Ankit Panda of the U.S.-based Carnegie Endowment for International Peace.

"Kim also appears to suggest that North Korean tactical nuclear weapons designs may primarily rely on uranium for their cores," he said.

This is notable because North Korea is more able to scale up its highly enriched uranium stockpiles, Panda said, compared to the more complicated process for plutonium.

'INCREASING ARSENALS'

North Korea invited some foreign scientists to view a centrifuge facility at Yongbyon in 2010, but Jenny Town of the U.S.-based Stimson Center said Friday's report is the first and only photographs of the equipment.

"It shows how advanced their enrichment capability has become, which gives greater credibility to both their ability and commitment to increasing their nuclear weapons arsenals," she said.

It could also be meant to influence the U.S. election and send a message to the next administration that denuclearisation is no longer possible and it should recognise North Korea as a nuclear state, said Hong Min, a senior researcher at the Korea Institute for National Unification in Seoul.

North Korea has previously shown photos of what it says were nuclear warheads. It has conducted six underground nuclear tests between 2006 and 2017.

Estimates of the number of North Korean nuclear weapons varies widely. In July a report by the Federation of American Scientists concluded that the country may have produced enough fissile material to build up to 90 nuclear warheads, but that it has likely assembled closer to 50.

Kim also oversaw the test launch of a new 600mm multiple launch rocket system on Thursday and visited an army training base on Wednesday, according to separate KCNA reports.

The U.S. and British foreign ministers met President Volodymyr Zelenskiy on Wednesday on a visit interrupted by air raid warnings, unveiling new support but no breakthrough on the long-range strikes into Russia desperately sought by Ukraine, Reuters reported.

U.S. Secretary of State Antony Blinken and British foreign minister David Lammy, in Kyiv at a critical juncture in Ukraine's struggle against Russia, said they talked about Ukraine's war goals and what they could do to help.

"Among other things, we discussed long-range fires, but a number of other things as well. And as I said at the outset, I'm going to take that discussion back to Washington to brief the president on what I heard," Blinken told reporters.

Zelenskiy has been pleading with Kyiv's allies for months to let Ukraine fire Western missiles including long-range U.S. ATACMS and British Storm Shadows deep into Russian territory to limit Moscow's ability to launch attacks.

"We are listening carefully and, of course, we are having discussions on a range of issues, including the military equipment that Ukraine needs to win," Lammy told a news conference alongside Blinken and Ukraine’s Foreign Minister Andrii Sybiha.

The British foreign minister suggested those discussions could continue for a few more weeks, a remark that will disappoint Ukrainians hoping the West would quickly discard fears of escalation.

Ahead of the news conference, Zelenskiy was asked whether he was optimistic the United States and Britain would greenlight deeper strikes into Russia, and he quipped that it depended instead on the "optimism" of Ukraine's partners, read the report.

"Let's count on some strong decisions at least. For us it's very important for today," he told reporters in Kyiv.

In a comment posted on his Telegram channel, Zelenskiy described the talks as "long and meaningful".

"All the key issues were discussed," he wrote.

"What's important is that all the Ukrainian arguments were heard. And that concerns long-range weaponry, supplying our front-line brigades and the general strategy of moving strategically towards a just peace."

There is nervousness in Washington and some European capitals that lifting the restrictions on long-range attacks could provoke Russia towards a direct conflict with the West, at the same time as a recognition that Ukraine needs more help if it is to swing the war in its favour, Reuters reported.

The speaker of Russia's lower house of parliament, Vyacheslav Volodin, said Moscow would consider the United States and its allies to be parties to the war if they allowed Kyiv to use long-range weapons to strike deep in Russia.

Overnight, U.S. President Joe Biden suggested there was room for compromise, saying his administration was "working that out now" when asked if the United States would lift the restrictions on the use of long-range weapons.

The air raid alert sounded twice during Blinken and Lammy's visit to Kyiv, before and after the news conference. A wreath-laying ceremony they were due to attend was cancelled.

Both alerts appeared to have been sounded over ballistic missile threats, but it was unclear what any missile had been targeting or what happened to the missiles.

Blinken announced more than $700 million in support for Ukraine. Lammy said Britain would provide a further 600 million pounds ($781 million).

More than 2-1/2 years since the invasion, Russian forces are inching forward in the east as Kyiv's forces try to hold a pocket of land they seized in western Russia in a surprise incursion last month.

After making rapid progress initially, Ukrainian advances have stalled, and on Wednesday a senior Russian commander said his forces had taken back control of about 10 settlements.

Ukraine has not commented on the latest Russian reported gains. Reuters was not able to independently verify battlefield developments, read the report.

Later this month, Zelenskiy travels to the United States and will present a plan to Biden and his two potential successors in November's presidential election that he hopes will bring the end of the war closer.

Israeli airstrikes on a tent camp for displaced Palestinians killed and wounded 65 people in southern Gaza, the enclave's civil emergency service said early on Tuesday, as the Israeli military said it had targeted a Hamas command center, Reuters reported.

Residents and medics said a tent encampment near Khan Younis in the Al-Mawasi area, a designated humanitarian zone, was struck by at least four missiles. The camp is crowded with displaced Palestinians who have fled from elsewhere in the territory.

The Gaza civil emergency service said at least 20 tents caught on fire, and missiles caused craters as deep as nine meters (30 feet). It said the 65 victims included women and children but did not provide a breakdown of deaths and injuries.

There was no immediate comment from the Gaza health ministry, which compiles casualty figures. Earlier, the Hamas-aligned Shehab News Agency said 40 Palestinians were killed.

"Our teams are still moving out martyrs and wounded from the targeted area. It looks like a new Israeli massacre," a Gaza civil emergency official said.

The official added that teams have been struggling to search for victims who might have been buried, read the report.

The Israeli military said it "struck significant Hamas terrorists who were operating within a command and control centre embedded inside the Humanitarian Area in Khan Younis."

"The terrorists advanced and carried out terror attacks against IDF troops and the state of Israel," the statement said, referring to the Israeli Defence Forces.

Hamas, the Islamist group that controlled Gaza before the conflict, denied Israeli allegations gunmen existed in the targeted area, and rejected accusations it exploited civilian areas for military purposes.

"This is a clear lie that aims to justify these ugly crimes. The resistance has denied several times that any of its members exist within civilian gatherings or using these places for military purposes," said Hamas in a statement.

Ambulances raced between the tent camp and a nearby hospital, while Israeli jets could still be heard overhead, residents said.

Nearly all of Gaza's 2.3 million people have been forced from their homes at least once, and some have had to flee as many as 10 times, Reuters reported.

The war was triggered on Oct. 7 when Hamas attacked Israel, killing 1,200 and taking about 250 hostages, according to Israeli tallies. Israel's subsequent assault on Gaza has killed more than 40,900 Palestinians, according to the enclave's health ministry.

The two warring sides each blame the other for a failure so far to reach a ceasefire that would end the fighting and see the release of hostages.