Three Canadian Nato soldiers have been killed by a roadside bomb in southern Afghanistan, military officials say.
This year has seen the heaviest fighting since 2001
Their vehicle was "struck by an improvised explosive device", the 37-nation force said in a statement.
A Nato spokesman said that the soldiers were in a small open-top all-terrain vehicle when the bomb went off.
About 90 foreign troops have been killed in Afghanistan this year, most in combat for the Nato-led military force Isaf in the country's south.
The incident was one of several violent attacks in Afghanistan on Tuesday and Wednesday.
"Isaf is saddened by the deaths of these fine individuals," spokeswoman Lt Col Maria Carl said.
"Through their service they contributed to ensuring a safe and prosperous future for Afghanistan."
This week, BBC News is taking an in-depth look at the challenges facing Afghanistan's people and the peacekeepers.
Stories include: the state of the Taleban; corruption; the drugs problem; and attacks on schools.
Correspondents say that the south of the country has this year seen the worst violence since the Taleban were ousted from power in 2001 by an international coalition.
Most of the soldiers deployed there are British, Canadian, Dutch or American.
Afghan officials told the AP news agency that Nato-led and Afghan troops fought with the Taleban in Kandahar province on Wednesday, and called in air strikes.
They say that 21 militants were killed in six hours of fighting.
Correspondents say that it is impossible to verify the Nato claims.
In other incidents, gunmen are reported to have opened fire on people attending a mosque in eastern Afghanistan, before fleeing.
Police told AP that three people were reported to have been killed, and four others wounded. They said that the attackers fled without being caught ,and their motives were unknown.
Gunmen are also reported to have ambushed a convoy belonging to a senior UN official on the highway linking Kabul to Kandahar.
Two guards were reported to have been killed and another wounded.
In an interview with the BBC, the Afghan defence minister, General Abdul Rahim Wardak, said that he believed support for the Taleban insurgents was diminishing.
"At the moment you see the tides are turning in our favour, the Taleban have failed to materialise their so called spring offensive, they have failed to isolate Kabul or to cut highways or to expand their area of influence," he said.
"And now a lot of people are turning against them and they're supporting the government."