Former president of Afghanistan Burhanuddin Rabbani — Photo by AP

KABUL: Afghanistan said on Sunday that the suicide bomber who assassinated Afghan peace negotiator Burhanuddin Rabbani was a Pakistani national.

Tensions between the neighbours have been rising amid allegations from Afghan officials that Pakistan and its powerful ISI intelligence agency masterminded Rabbani's assassination and are seeking to destabilise Afghanistan.

An investigative delegation established by President Hamid Karzai said evidence and a confession provided by a man involved in Rabbani's killing on Sept. 20 had revealed that the bomber was from Chaman and the assassination had been plotted in Quetta, both on the Pakistani side of the border.

“It proves that the assassination of Professor Rabbani was hatched in Quetta and the man who carried out the suicide bombing is a Pakistani national,” the delegation, led by Defence Minister Abdul Rahim Wardak, said in a statement issued by the presidential palace.

“The documents and evidence in hand, details of other accomplices and their phone numbers have been handed over to Pakistan to make arrests,” it said.

Rabbani's killing derailed efforts to forge dialogue with the Taliban to end the 10-year war, and raised fears of a dangerous widening of Afghanistan's ethnic rifts.

The High Peace Council, which Rabbani headed, reiterated earlier comments by Karzai that negotiations should continue, but with Pakistan, rather than the Taliban.

“For the groups that are tired of conflict and want to end the killings and destruction inside the country, peace efforts must continue,” the council said in a separate statement issued late on Sunday.

“But because of those who hide in Pakistan with no known address, who send killers (to Afghanistan), we must negotiate with Pakistan instead.”

Hundreds of Afghans took to the streets of Kabul on Sunday to condemn recent shelling of border towns by Pakistan's army and accuse the ISI of involvement in Rabbani's killing.