Two NATO soldiers died when their helicopter crashed in eastern Afghanistan on Monday, the military said, taking the NATO death toll to 10 in three days.
"The cause of the crash is under investigation, however initial reporting indicates there was no enemy activity in the area at the time of the crash," the International Security Assistance Force (ISAF) said.
ISAF did not reveal the nationalities of the victims.
Another NATO aircraft crashed during routine operations in eastern Afghanistan earlier Monday with no fatalities, the military said separately.
Taliban insurgents claimed in text messages to journalists that they had shot down two NATO helicopters.
In the south, an ISAF soldier also died Monday "following an insurgent attack," the alliance said.
On Sunday, three troops were killed, while on Saturday four died in separate bomb blasts in the south.
The latest deaths take the toll among NATO troops in Afghanistan this year to 175 and the total in 10 years of war to 3,022, according to an AFP count based on records kept by icasualties.org.
NATO has some 130,000 troops in Afghanistan but they will withdraw by the end of 2014, leaving the fight against Taliban insurgents to Afghan forces.
The Taliban have stepped up their attacks across the country since announcing the start of their spring offensive at the beginning of May.
But NATO deaths so far this year are down compared to the same period last year.
In April 2011, for example, 51 NATO soldiers were killed compared to 39 in April 2012. (KABUL - Agence France-Presse)