More than 2,000 Afghans protested outside the main U.S. military base in Afghanistan on Tuesday over a report that foreign troops had improperly disposed of copies of the Koran and other religious items, Afghan officials said.
U.S. helicopters fired flares to try to break up the demonstrators, some of whom were chanting anti-foreigner slogans and throwing stones.
Roshna Khalid, the provincial governor's spokeswoman, said Korans had been burnt inside Bagram airbase, an hour's drive north of the capital Kabul, citing accounts from local laborers.
"The laborers normally take the garbage outside and they found the remains of Korans," she said.
The top NATO general in Afghanistan attempted to contain fury over the incident, which could be a public relations disaster for the U.S. military as it tries to pacify the country ahead of the withdrawal of foreign combat troops in 2014.
"When we learned of these actions, we immediately intervened and stopped them. The materials recovered will be properly handled by appropriate religious authorities," said General John Allen, head of the International Security Assistance Force (ISAF), in a written statement, as well as in a video released on a U.S. military website.
"This was NOT intentional in any way."
The protests took place outside Bagram.
"There are about 2,000 to 3,000 demonstrators, throwing stones at the base and chanting down with the foreigners," said Rahman Sayedkhili, a senior police officer in Parwan province, where Bagram is located.
A Reuters reporter at one of Bagram's gates said flares were fired from U.S. helicopters in a bid to disperse the crowd.
Bagram also houses a prison for Afghans detained by American forces. The centre has caused resentment among Afghans because of reports of torture and ill-treatment of suspected Taliban prisoners, with President Hamid Karzai demanding the transfer of prisoners to Afghan security.
Allen did not provide details on the incident. The Koran is the holy book of Islam.
Winning the hearts and minds of Afghans is critical to U.S. efforts to defeating the Taliban, but critics say Western forces often fail to grasp Afghanistan's religious and cultural sensitivities.
"I offer my sincere apologies for any offence this may have caused, to the president of Afghanistan, the government of the Islamic Republic of Afghanistan, and most importantly, to the noble people of Afghanistan," said Allen.
Protests raged for three days across Afghanistan in April last year after a U.S. pastor burned a Koran in Florida.
Eleven people were killed when demonstrators stormed a U.N. compound in the northern city of Mazar-i-Sharif, including seven foreign U.N. workers. Another riot in the southern city of Kandahar left nine dead and more than 80 wounded.