Nato led International Security Assistance Force investigate the scene of a road side bomb in Ghazni, southwest of Kabul, Afghanistan. - AP Photo.

KABUL: A roadside bomb attack killed three Nato troops in eastern Afghanistan, one of the deadliest flashpoints in the 10-year war against Taliban insurgents, the military said Wednesday.

Nato's US-led International Security Assistance Force (ISAF) did not release the nationalities of the troops or give further details of the incident, which happened on Tuesday.

The deaths take to 561 the number of foreign troops killed in Afghanistan so far this year, according to an AFP tally based on figures from independent website iCasualties.org.

A total of 711 foreign troops were killed in Afghanistan last year, the highest annual total since the US-led invasion in 2001 ousted the Taliban from power.

There are about 130,000 international troops in Afghanistan fighting the Taliban-led insurgency, with 91,000 of them from the United States.

Much of the worst fighting takes place in the east of the country, close to the border with Pakistan, where US and Afghan officials say the Taliban use rear bases to regroup and plot attacks.

Pakistan closed its supply routes to Nato after US air strikes killed 24 Pakistani soldiers on November 26 close to the mountainous, porous border.

Amid declining support for the war and a gloomy economy in the West, all foreign combat troops are due to withdraw from Afghanistan by the end of 2014, by which time Afghan forces and officials are supposed to take full control.

On Tuesday, President Hamid Karzai called on Nato to disband an irregular security force operating in northern provinces, saying it had been set up “unilaterally” without coordination with the Afghan government.

Nato said Wednesday that all such security programmes are being disbanded or shifted to Afghan government control.

ISAF said the Critical Infrastructure Protection Programme, which involves more than 1,500 personnel, had been one of several units set up to bolster security while regular Afghan forces were building to full strength.

Human rights groups warn that US-funded local armed groups sometimes used to fill the void in security have been linked to abuses, violence and extortion.