Seven people were killed today in clashes between Afghan security forces and protesters demonstrating against the burning of Muslim holy books at a Nato military base.
The anger over the Koran burning has sparked two days of protests across Afghanistan and tapped into anti-foreign sentiment fuelled by a popular perception that foreign troops disrespect Afghan culture and Islam.
The demonstrations prompted the US to lock down its embassy and bar its staff from travelling.
The Afghan Interior Ministry said in a statement that clashes during a protest in the eastern province of Parwan left four people dead. It said an investigation was under way to determine what happened.
The other deaths occurred at a US base outside Kabul, where security guards killed one person, and in Jalalabad and Logar province, the ministry said.
The demonstration in Kabul drew thousands of protesters, who chanted "Death to America", hurled rocks and set tyres alight outside a complex that is home to foreign contractors, police and some coalition military forces.
Nearby, angry demonstrators set a fuel truck ablaze on a main highway running east out of the city, sending black smoke billowing into the air.
The US apologised for burning the copies of the Koran, which had been pulled from the shelves of the Parwan Detention Facility, adjoining Bagram Air Field, because they contained extremist messages or inscriptions.
US General John Allen, the top commander of American and Nato forces in Afghanistan, said the books had been mistakenly given to troops to be burned at a garbage pit without realising it.
He said: "It was not a decision that was made with respect to the faith of Islam. It was a mistake. It was an error. The moment we found out about it we immediately stopped and we intervened."
A Western military official with knowledge of the incident said it appeared that the copies of the Koran and other Islamic readings in the library were being used to fuel extremism, and that detainees were writing on the documents to exchange extremist messages.
As Wednesday's rally in Kabul turned violent, city police chief Mohammad Ayub Salangi arrived at the scene with hundreds of reinforcements who broke up the protest.
"They have the right to demonstrate, but they have to do it in accordance with the law," said his deputy, Daud Amin.
Several miles away, hundreds of protesters were throwing rocks at Camp Phoenix, a US military base, said Kabul provincial police spokesman Ashmatullah Stanekzai. Shots were also fired in the air at Camp Phoenix.
After the Koran burning was made public on Tuesday, more than 2,000 Afghans protested outside the Bagram air base near the capital.
In Parwan, provincial police chief Akram Bigzad said about 2,000 protesters were demonstrating outside a district headquarters when some of them opened fire with weapons.
"In the crowd there were rebels and Taliban who had weapons. They opened fire and fighting started. Four were killed and 10 were wounded. They are Talib," he said.
A protest in Logar province also turned violent after someone in a group of about 300 demonstrators opened fire on police. Police returned fire, killing one protester, said provincial police chief General Ghulam Sakhi Roogh Lawanay.
Two protesters and two police officers were also wounded, he added.