Five Nato troops have died in southern Afghanistan, days before the next round of the country’s Presidential election.
The International Security Assistance Force (Isaf) said they died on Monday in Zabul province but gave no more details.
Local police and the Taliban claimed the troops were killed by “friendly fire” when they were hit by an air strike by allied helicopters while fighting insurgents.
Ghulam Sakhi Roghlewai, a police chief, said: “Isaf troops were returning to their bases after an operation when they were ambushed by the insurgents. The air strike mistakenly hit their own forces and killed the soldiers.”
A Taliban spokesman, Qari Yousuf Ahmadi, said insurgents had been attacking the foreign forces when the helicopters intervened and accidentally killed their own troops.
Security is being increased in Afghanistan ahead of Saturday's run-off vote to replace President Hamid Karzai.
The poll pits Abdullah Abdullah, a former leader of the opposition to the Taliban, against the former Finance Minister, Ashraf Ghani.
The Isaf said it was investigating the deaths.
A Ministry of Defence spokesman confirmed the dead soldiers were not British. There are soldiers from 50 nations fighting in Afghanistan.
Since the start of the Afghan conflict in 2001, 453 British servicemen and women have been killed.
Additional reporting by Reuters