More than 670 foreign troops have been killed in Afghanistan this year [File: EPA/ISAF]

At least six soldiers serving with the NATO-led force in Afghanistan have been killed in an attack by suspected Taliban forces.

The International Assistance Security Force (ISAF) did not release any other details of the identities of the foreign troops who died in fighting in the south of the country on Sunday.

It is the highest death toll in a single incident since since six troops were shot dead on November 29 by a renegade border policeman.

Fighting has increased in southern Afghanistan as additional US troops have been poured into Helmand and Kandahar provinces in an attempt to push the Taliban out of their traditional strongholds.

More than 670 international troops have been killed so far this year, well above the 502 killed in the whole of 2009.

Source: Agencies