The latest deaths bring the overall number of foreign troops killed in Afghanistan this year to 426, compared to 520 for all of 2009, according a tally kept by icasualties.org, an independent monitoring group.
Elsewhere, seven suspected fighters were killed and five people were wounded, including four US soldiers, when anti-government fighters attacked three Nato combat posts on Monday, Nato said.
The attack happened in the rural province of Paktika, which shares a long, porous border with Pakistan and is seen as a hotbed of Taliban activity.
"The attack ... [lasted] for four hours," US Air Force Master Sergeant Lori Mills said.
"Seven enemy, among them suicide attackers, tried to attack three Afghan and coalition posts," she said.