The incident happened on Friday when a small number of furious protesters stormed the UN headquarters in the northern Afghan city of Mazar-i-Sharif, The New York Times quoted police spokesman Lal Mohammad Ahmadzai as saying.

The armed men killed 10 foreign staff members whose nationalities were not immediately clear. Eight of the victims were shot to death while two others were beheaded after being captured.

Local medics confirmed receiving 24 wounded and five dead Afghan civilians. Other reports said that the five dead Afghans included some of the guards at the UN building.

Unconfirmed Afghan media reports said that the head of the United Nations mission in the city was among the dead.

A spokesman for the United Nations Assistance Mission in Afghanistan, Kieran Dwyer, said the attack had occurred during a demonstration.

“We can confirm there have been casualties, including UN personnel, but the situation on the ground remains very confusing,” he said, adding that the world body’s top official in Afghanistan, Staffan de Mistura, was heading for Mazar-i-Sharif.

The demonstration came after the Friday Prayers in protest at the burning of a copy of the Muslim holy book by an American pastor in Florida and was attended by thousands of angry Afghans.

On March 20, Pastor Terry Jones, who had already caused an outrage worldwide by threatening to burn copies of the Qur’an last September, broke his earlier promise and burned the Qur’an after holding a mock trial at his fringe church in Gainesville.

Similar protests have been held in the western city of Herat and the capital Kabul, where demonstrators marched on to the UN building to also protest the permanent US military bases in Afghanistan.

Afghan President Hamid Karzai has strongly condemned sacrilegious acts against the holy book of Qur’an in the United States.

The presidential office on Thursday described burning of the holy Qur’an at a Florida church as “disrespectful and abhorrent”.

“President Karzai on behalf of the Muslim people of Afghanistan and on his own behalf denounced the disrespectful and abhorrent act,” said a statement from Karzai’s office.

Karzai also called on US officials to bring those responsible for the burning of the Islamic holy book to justice.