A bomb dropped by a U.S. fighter jet was believed to have killed three British soldiers in southern Afghanistan, NATO and British officials confirmed Friday. Two other soldiers were injured.

Britian's Ministry of Defense said the troops, from 1st Battalion The Royal Anglian Regiment, were patrolling northwest of Kajaki in Helmand province on Thursday evening when they were attacked by Taliban insurgents.

The ministry said that "during the intense engagement that ensued, close air support was called in from two U.S. F15 aircraft to repel the enemy. One bomb was dropped and it is believed the explosion killed the three soldiers. "

The military did not identify the soldiers but said next of kin had been informed.

A NATO spokesperson said an investigation into the incident would be held.

Earlier this year, Defense Secretary Des Browne said that since 1990, 12 British personnel had died in friendly fire incidents involving U.S. forces in Iraq, but that no such incidents had taken place in Afghanistan.

Britain has about 7,000 troops in Afghanistan, most based around restive Helmand Province in the south. The latest deaths bring to 73 the number of British personnel killed in the country since the U.S.-led invasion in November 2001.

Joint operations between U.S. and British forces in Iraq have been marred by "friendly fire" deaths caused by the failure of equipment and personnel in correctly identifying personnel.

After an inquest into the death of British soldier Lance Cpl. Matty Hull, 25, killed in a friendly fire attack by two American pilots in Iraq in 2003, opposition legislators in Britain called for improvements in joint identification systems.

Britain last year threatened to end cooperation with the U.S. on the new Joint Strike Fighter jet after 10 years of development, until the Pentagon resolved concerns it was not sharing enough information about the aircraft's sensitive software with London.