Afghanistan’s First Vice President, Amrullah Saleh, said on Wednesday that they have arrested another suspect behind the deadly attack on Kabul University early this month.

According to Saleh the person, named Rahmatullah, has been taken into custody and is believed to have been one of the masterminds behind the attack that killed at least 22 people, mostly students.

The university attack came just a week after a previous bombing outside another education facility in Kabul that killed 24 students.

In both instances ISIS (Daesh) claimed responsibility.

On Wednesday, Saleh said: “Kabul University and Kosar Danish cases are a crime against humanity and we bring together Afghans and the world against the crime. We hope that the human rights commission ignores criticisms and works practically.”

Saleh’s remarks came after the Afghanistan Independent Human Rights Commission (AIHRC) stated that “students and educators must be ensured safety and security while attending school, without any threat or fear for their lives and to be able to work, study, and learn in a protected and safe environment.”

Professors, lecturers and students from universities around the world also weighed in this week and signed and sent out a letter condemning attacks on educational facilities in Afghanistan and listed their demands.

Signatories were from academics at top universities, including Stanford and University of California.

They demanded that the Afghan government, the United States, the European Union, and other international stakeholders use their influence to investigate and prosecute the perpetrators of these “calculated attacks on civilian populations and protected sites, such as universities and educational centres.”

They also called for the rights of students and educators to be safeguarded and hold all actors engaged in the war in Afghanistan accountable and pressure them to comply with the Geneva Convention and respect civilian lives during war.

Saleh’s announcement meanwhile came after his recent statements that in addition to this arrest, another two key planners of the attack are in custody while a third was killed in an operation by security forces.

On Saturday, Saleh said at a high-ranking security meeting that a member of the Taliban's Haqqani Network was behind the attack.

He said the country's intelligence agency NDS had taken the main perpetrator, identified as Aadil, into custody and that this suspect had once studied at Kabul University’s faculty of Sharia before joining the Taliban.

Saleh also said on Facebook the suspect told officials that the Taliban had aimed to defame the government and make it appear weak.

But the Taliban has rejected government accusations of involvement in the latest attack.

"Claim by #Kabul admin deputy [vice president] of detaining #Kabul Uni attackers & linking them to Haqqani Sahib's personnel are fabrications. All these allegations are an attempt to divert attention away from joint #Kabul-#ISIS crime & deceive the public," the group's spokesman Zabihullah Mujahed tweeted.

The attack was widely condemned by the Afghan government and the international community.