Five soldiers from the U.S.-led international force in Afghanistan have been killed in two separate attacks.

Four soldiers were killed when insurgents opened fire on their convoy following a roadside blast on the west side of Kandahar city around 8 a.m. local time Saturday, officials said.

Two other soldiers were seriously injured in the attack.

Military officials did not reveal their nationalities, but CBC News has been told that no Canadians were among the casualties.

Elsewhere, a Polish soldier was killed and four others wounded when an improvised explosive device went off in the southeastern province of Paktika shortly after midnight.

The bombings cap a deadly week in Afghanistan, particularly regions north of Kandahar city, the former seat of government for the Taliban.

Coalition forces and Afghan troops backed by warplanes on Wednesday attacked up to 400 Taliban militants who had seized Arghandab, a strategic valley located within striking distance of Kandahar.

According to the Afghan defence ministry, 56 fighters and two Afghan soldiers died during the overnight operation in several villages, though the provincial governor put the militants' death toll at more than 100.

Gov. Asadullah Khalid also said villagers reported some militants spoke the Pashto dialect of tribes from across the border in Pakistan who are suspected of harbouring insurgents.

On Thursday, coalition forces issued a statement saying the valley and its swath of farmland is secure enough for villagers to return home.

With files from the Associated Press