Several US troops have been killed by a man wearing Afghan military uniform. Others were wounded in the attack at a remote base in eastern Afghanistan. It is not known if the families of the dead and injured have been informed and their names have not yet been released.
Afghan officials said the shooting happened in Wardak province, where the Afghan government had demanded the withdrawal of US special forces over allegations of disappearances and torture by Afghan troops working with them.
The latest deaths come amid continuing tension between the Afghan government and the US, as Nato troops prepare to end combat operations next year.
Afghan President Hamid Karzai has been strongly critical of US and allied forces for causing civilian casualties.
So-called “insider attacks” by members of the Afghan security forces or insurgents posing as them account for a growing proportion of Isaf casualties.
Earlier on Monday, police in the Afghan capital Kabul said two civilian lorry drivers were killed and one wounded when they were fired on by an Isaf convoy.
Last year more than 60 Nato troops were killed by rogue members of the Afghan security forces.