NATO has recalled all its staff working in ministeries in and around the Afghan capital Kabul as anti-Western protests rage for a fifth day.
The move comes after the Taliban said it killed two Americans, believed to be senior army officers.
The pair were shot dead inside the heavily barricaded Interior Ministry in retaliation for the burning of copies of the Koran at a NATO base in Bagram.
The desecration of the Muslim holy book has fuelled anger and deepened mistrust of alliance forces struggling to stabilise Afghanistan before foreign combat troops withdraw in 2014.
Despite an apology from U.S. President Barack Obama and a call for restraint from his Afghan counterpart, Hamid Karzai, thousands have taken to the streets after 12 people were killed and dozens wounded on Friday, the bloodiest day yet in demonstrations.