NATO's Resolute Support mission said in a statement on Sunday that three NATO forces were killed by a suicide bomber during a mission in eastern Afghanistan .
The NATO mission added that a US member of the patrol and two Afghan soldiers were also wounded.
It did not mention the nationality of those killed.
The attack by a lone bomber on foot happened at 6am in the city of Charikar in Parwan province 60 kilometres (37 miles) north of Kabul, said provincial governor's spokesman Wahida Shahkar.
The Taliban in a statement claimed responsibility, saying they killed or wounded eight American soldiers in a "tactical explosion".
The NATO force largely ended its combat mission in Afghanistan in 2014 and pulled out the bulk of its troops.
A 16,000-strong residual force remains for training and counter-terrorism operations.
Of these, the US accounts for 13,000 soldiers, about 2,000 of whom are assigned to anti-terror combat missions, still fallen behind that.
