Afghans gather to mourn Burhanuddin Rabbani
Hundreds of Afghans have gathered in Kabul to mourn High Peace Council chief Burhanuddin Rabbani and protest at his killing by a suicide bomber on Tuesday.
Kabul was gridlocked as streets were shut off near Mr Rabbani's home, where ex-colleagues arrived to pay respects.
Mr Rabbani, head of the council charged with talking to the Taliban, was killed by a bomb hidden in a turban.
President Hamid Karzai cut short his visit to the UN in New York and has returned to Afghanistan.
The BBC's David Loyn in Kabul says black awnings were draped over the streets close to Mr Rabbani's home as a mullah's chants carried through the air.
Former warlords were among those paying respects, he says, arriving in cars with blackened windows.
There was heavy security in Kabul's diplomatic zone, where Mr Rabbani's house is located, with police searching all those arriving.
Several hundred people, many wearing black headbands, carried pictures of Mr Rabbani and chanted Koran verses.
One mourner, Hayatullah, told Reuters: "We came to express our condemnation to the enemies of peace and stability, the enemies of our country and government. We condemn the assassination of our jihad and resistance leader."
Kabul resident Mirza Mohammad told Associated Press: "He wanted peace in Afghanistan and sacrificed his life on the path of bringing peace."
Three days of mourning have been announced in Afghanistan for Mr Rabbani, who is to be given a state funeral.
Some reports say that he will be buried in his home province of Badakhshan in the north-east, others that it will be on a hilltop overlooking his Kabul home.
No-one has yet said they carried out the attack and our correspondent says it could be one of a number of insurgent groups.
On Wednesday, the Taliban issued their first public statement on the killing, saying they did not want to comment.
Spokesman Zabihullah Mujahid said: "Until we receive more information and our information is complete, our position is that we cannot say anything on this issue."
Mr Rabbani, 71, had been meeting Taliban commanders, returning from abroad a few days ago specifically for the talks.
Peace Council member Fazel Karim Aymaq said two visitors were invited to the meeting on Tuesday who said they had a "special message" from the Taliban and were considered "very trustworthy".
"One of them put his head on the shoulder of Rabbani and detonated the explosives hidden in his turban," Mr Aymaq said.
Senior Afghan officials told the BBC the visitors had a "fake letter" purporting to carry a special message from the Quetta region.
An aide close to the president said the High Peace Council thought this would be an important meeting and it was kept secret from all but a few people in the council.
Afghan intelligence officials said the council had made a mistake in not informing them as they could have investigated whether this "special message" was genuine.
Afghan foreign ministry spokesman Janan Mosazail told the BBC the killing would not stop the peace process.
He said: "Rabbani is not the first and he will not be the last prominent Afghan leader who has been killed by terrorists trying to derail the peace process. But we will continue with our efforts."
Our correspondent says the international community will want Mr Karzai to appoint another Peace Council head quickly to continue the work, but former members of the anti-Taliban Northern Alliance, made of mostly non-Pashtun ethnic groups, who have said peace talks will never work, will gain political strength from this killing.
Series of assassinations
When the High Peace Council was set up in October 2010, Mr Karzai described it as the greatest hope for the Afghan people and called on the Taliban to seize the opportunity and help bring peace.
But many members of the council are former warlords who spent years fighting the Taliban and their inclusion led to doubts as to whether it could succeed in its mission.
Our correspondent says Mr Rabbani's appointment as head was a surprise. Some had even called for him to be indicted for war crimes in his previous role with the mujahideen.
In the 1970s it was Mr Rabbani who founded the parties that ended up becoming the Afghan mujahideen who took on the Soviets, and many blame him and his friends for the death and destruction of the civil war days.
Mr Rabbani was ousted as president by the Taliban in 1996. After that he became the nominal head of the Northern Alliance.
When they swept back into Kabul, backed by US forces, and toppled the Taliban in 2001, he was still recognised by the UN as the official president of Afghanistan.
The killing is the latest in a series of assassinations of senior figures.
In July, President Karzai's half-brother Ahmed Wali Karzai was killed at his home in Kandahar. Two months earlier, Gen Daud Daud, the top police commander in northern Afghanistan was killed in a suicide bomb attack.