Britain's Defense Ministry says three British soldiers were killed and two others wounded in southern Afghanistan by a U.S. air strike that was supporting them in a battle with Taleban insurgents.
The ministry says the apparent "friendly fire" incident happened late Thursday in Helmand province after planes were called in to support the British troops.
In Washington, the U.S. State Department said in a written statement Friday that it was saddened by the casualties in the friendly fire incident.
Principal Deputy Assistant Secretary of State for European and Eurasian Affairs Kurt Volker said Washington will investigate the tragic incident thoroughly with its British allies.
In a separate incident Friday, the U.S. military said two coalition troops were killed and two others wounded when their vehicle overturned in western Herat province.
Also Friday, the U.S.-led coalition said troops killed a militant and detained 11 other people during a raid in the eastern province of Nangarhar.
The statement said the fighter was killed when he tried to attack coalition and Afghan forces.
In other violence, Afghan officials say a rocket was fired into the Afghan capital, Kabul, on Friday. No injuries were reported.