KABUL, Afghanistan — Three Georgian soldiers were killed in southern Afghanistan on Monday when insurgents detonated a vehicle laden with explosives, a senior Western military official and NATO said.

The deaths take the number of troops killed in Afghanistan from the former Soviet, non-NATO country to 22. With over 1,500 soldiers serving in Helmand province, Georgia has the largest non-NATO combat troop commitment in Afghanistan.

Georgian media reports quoted Georgian Defense Minister Irakly Alasania as saying that a suicide bomber drove a truck full of explosives into their base in Helmand.

Georgian troops have been in Afghanistan since 2004, a commitment that underscores Tbilisi's ambition to join NATO, despite fierce opposition from neighbouring Russia, with which it fought a brief war in 2008.

"Two Georgians died on the spot, a third died of wounds," said a senior Western military official in Kabul, speaking on condition of anonymity.

May has proved particularly bloody for members of the NATO-led International Security Assistance Force (ISAF), which is preparing to withdraw all combat troops by the end of next year.