At least five US soldiers serving as part of the NATO forces have been killed by a roadside bomb in southern Afghanistan, officials have said.

The troops died in an improvised explosive device (IED) attack, NATO's International Security Assistance Force confirmed in a statement on Saturday.

"Five American soldiers were killed at about noon when their armoured vehicle hit a powerful roadside mine in Maiwand district," Kandahar province's police chief General Abdul Razeq told AFP news agency.

Kandahar governor spokesperson confirmed the incident and said that the incident happened in Maiwand district of Kandahar province when road bomb exploded on a NATO patrol in the area.

Maiwand borders Helmand province to the west and is considered one of the most volatile of Kandahar's districts.

In another incident two NATO service members were killed when an Afghan National Army Soldier turned his weapon against them in the west of the country.

Last month nine Afghan men working for a mine clearance organisation were taken captive by Taliban fighters there, though they were later released.

It is the biggest attack since the Taliban launched their annual spring offensive on Sunday, saying it would take aim at foreign military bases and diplomatic areas.

The attack came four days after three British soldiers were killed in a similar attack in the neighbouring province of Helmand.

Nineteen US personnel have been killed in the last week in three air crashes and Saturday's bombing.

Source: Agencies