The American Embassy said its staff were in "lockdown" and travel had been suspended as thousands of people expressed fury over the burning, a public relations disaster for U.S.-led NATO forces fighting Taliban militants ahead of the withdrawal of foreign combat troops by the end of 2014.

The U.S. government and the American commander of NATO-led forces in Afghanistan apologized after Afghan laborers found charred copies of the Koran while collecting rubbish at the sprawling Bagram Airbase about an hour's drive north of Kabul.

It failed to contain the fury. Thousands of Afghans took to the streets again, chanting anti-American slogans.