Kabul - A suicide attack on a joint Nato-Afghan foot patrol on Monday killed at least 13 people, including three Nato troops and four Afghan police, ISAF and Afghan officials said.
Six civilians were also killed and 37 were wounded in the attack near a market in the eastern city of Khost, the provincial governor's office said.
"Today at around 08:30 a suicide bomber on a motorcycle targeted a joint patrol in Khost city in a crowded area.
"In this inhuman attack three police and 37 civilians were wounded, and six civilians and four police, including the commander of the quick reaction forces, were killed," the governor's office said in a statement.
Hospital sources put the number of Afghan dead at 10 with more than 60 wounded.
A spokesperson for Nato's US-led International Security Assistance Force said he could confirm that three Nato service members had been killed, but that details of the incident were still unclear.
The deaths take coalition casualties to at least 347 this year, according to an AFP tally.
Nato has more than 100 000 troops fighting a Taliban insurgency in Afghanistan, but they are due to pull out by the end of 2014.
The latest blast came a day after Nato announced that a firefight between coalition troops and their Afghan allies killed an ISAF soldier, a civilian contractor and three Afghan army troops in circumstances that remained murky.
The incident was initially described as a suspected insider attack, but it was later suggested that either insurgent fire or a verbal argument between the troops sparked the shooting.