World leaders have condemned the Taliban's assassination of Afghan peacebroker Burhanuddin Rabbani.
Professor Rabbani, a former president of Afghanistan who was in charge of peace talks between the government and insurgents, was killed at home in Kabul by a suicide bomber posing as a peace negotiator.
Counter-terrorism officials have told the BBC two Taliban commanders arrived with a senior adviser to the High Peace Council, Masoom Stanakzai, to meet Professor Rabbani for talks.
The officials say that as guards approached to search the men, Mr Stanakzai shouted: "We know them. They are our own people."
As one of the Taliban commanders went to embrace Professor Rabbani, he detonated explosives concealed in his turban.
The officials say Mr Stanakzai was seriously injured and the head of one of the attackers was blown off. The other attacker was injured and has been arrested.
Karzai cuts short UN visit
British Prime Minister David Cameron says he is "absolutely appalled" by the assassination, AFP reports, and French president Nicolas Sarkozy says the killing is a "terrorist act of unbearable cowardice".
United Nations Secretary-General Ban Ki-moon says he is deeply shocked and condemns "in the strongest possible terms this attack on people who were working to bring peace in Afghanistan".
United States President Barack Obama describes the killing as "a senseless act of violence" and offered condolences when he met Afghan president Hamid Karzai in New York.
Mr Karzai has since cut short his visit to the UN General Assembly and headed home.
While world leaders say Professor Rabbani's death will not derail peace efforts, the US military says the attack shows the Taliban are changing tactics by moving off the battlefield to go after high-profile targets elsewhere.
Controversial figure 'with many enemies'
Burhanuddin Rabbani was a former leader of a powerful mujahideen party during the Soviet occupation of Afghanistan in the 1980s.
He was president of Afghanistan for four years until ousted by the Taliban in 1996. After that, he became the nominal head of the anti-Taliban Northern Alliance.
In October 2010, Mr Karzai chose him to head the High Peace Council.
The BBC reports he was a controversial figure who had many enemies, and many were surprised when he was put in charge of peace talks.
