PESHAWAR: The Pakistani university attacked by Taliban militants in a deadly assault last week will remain closed indefinitely until security is beefed up, staff said on Tuesday, as some teachers demanded the government issue them with weapons.

Four Pakistani Taliban gunmen killed 21 people at Bacha Khan University in Charsadda in the country's northwest on Wednesday after scaling its rear walls, battling security guards and then firing into packed classrooms and hostels.

University staff and students met on Monday, after briefly reopening the campus, to review security as at least 200 students protested outside to demand the government protect them.

"We decided to keep the university closed for some time so we can repair the damaged building and further improve the security situation," Fazal Rahim Marwat, a professor at the university, told Reuters.

He said some teachers had demanded licensed weapons for self-defence, a suggestion that is rejected by other teaching members and has reignited a debate about arming school staff.

Educational institutions have become an increasingly common target for the militants waging war against the Pakistani state. In December 2014, gunmen killed 134 children at an army-run school in the city of Peshawar, about 30 km (19 miles) from the site of last week's attack.

Authorities say last week's assault was planned and carried out by Pakistani Taliban militants based in neighbouring Afghanistan. Five suspects have been arrested in Pakistan for acting as "facilitators".

Pakistan has launched a major crackdown against militants holed up along its porous border with Afghanistan, but the university attack shows they retain the capacity to launch deadly raids, particularly against targets where security is relatively weak.

The Pakistani Taliban commander who says his fighters were behind the Bacha Khan assault released a video last week vowing more attacks on schools.