Three troops from the NATO-led International Security Assistance Force (ISAF) have been killed by a roadside bomb in eastern Afghanistan, according to officials. ISAF did not say which country the dead troops were from or give further details of the incident, which happened Tuesday, in line with policy. There are around 130,000 international troops in Afghanistan fighting a Taliban-led insurgency. About 90,000 of them are from the United States. \"Three International Security Assistance Force service members died following an improvised explosive device attack in eastern Afghanistan yesterday,\" the statement said. Much of the decade-long Afghan war\'s worst fighting takes place in the east of the country, close to the border with Pakistan. Pakistan closed its supply routes to NATO forces in Afghanistan after 24 Pakistani soldiers were killed by a NATO air strike on November 26 close to the mountainous, porous border. Amid declining support for the war and fragile economies 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 to be in control of the country. President Hamid Karzai Tuesday 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 emphasised 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 men, was one of several other units set up to bolster security while regular Afghan forces were still building to full strength. \"ISAF remains committed to ensuring all armed security-related organisations fall within the sovereign control of the Afghan government, and specifically under the control of the ministry of interior,\" ISAF commander General John Allen said in a statement. \"ISAF will work with the ministry of interior to ensure these groups with association with ISAF are properly transitioned and disbanded.\" Human rights groups have warned that US-funded armed groups which are sometimes used to fill the void in security have been linked to abuses, including violence and extortion.