Two American soldiers have been shot dead at a base in Afghanistan, the latest in a series of deaths following the burning of Korans by US soldiers.
The shootings were carried out by an Afghan soldier and a literacy teacher, officials said,
Both were killed on the same day that the top Nato commander allowed a small number of foreign advisers to return to work at Afghan ministries after more than a week of being locked down in secure locations because of the killing of two other Americans.
The killings raised to six the number of Americans killed in less than two weeks amid heightened tensions over the February 20 burning of Korans and other Islamic texts that had been dumped in a rubbish pit at Bagram Air Field near Kabul.
More than 30 Afghans have also died in six days of violent riots that broke out after the incident.
President Barack Obama and other US officials apologised and said the burning was an accident.
Afghan security forces - or militants disguised in their uniforms - have staged a number of attacks against Americans and other members of the international alliance in recent years. But the recent deaths have been linked to the Koran burnings.
Details of the latest attack were still unclear but officials believe there were three attackers, two of whom were subsequently killed.
Hundreds of advisers were pulled out of ministries and other government locations after an Afghan gunman shot and killed two US military advisers on February 25 inside their office at the Interior Ministry.