The force, made up of about 50,000 soldiers from 40 countries, did not give the nationalities of the soldiers.
Most of the soldiers in eastern Afghanistan are from the US.
The new deaths bring to 67 the number of international soldiers who have died in Afghanistan this year, most of them in hostile action.
Saturday's blast came two days after a suicide car bomber killed three Afghan civilians in Kabul.
The Taliban claimed both attacks.
Governor killed
Separately, suspected Taliban fighters killed Gulab Shah Alikhail, a district governor, and his bodyguard in the southern Zabul province overnight, the deputy provincial governor told the AFP news agency.
In the same region, an Afghan soldier was killed in a battle with fighters in Shiwak district, Colonel Mohammad Gul, an Afghan army spokesman, said.
Later the interior ministry said that Afghan security forces backed by foreign military allies had killed more than 100 fighters and had retaken the remote district of Bakwa in the southwestern province of Farah.
The Taliban had captured the district eight months ago.
Authorities retook control on Friday, Zemarai Bashary, a ministry spokesman said.
"During two days of operations more than 100 enemies of peace and stability were killed," he said.