(Adds ISAF statement on civilian killing)

KABUL, Sept 30 (Reuters) - Three soldiers from a U.S.-led coalition force in Afghanistan have been killed in a blast in the south of the country, the U.S. military said on Tuesday.

Violence has surged in Afghanistan this year with about 3,000 people, at least 1,000 of them civilians, killed in the bloodiest year since U.S.-led and Afghan forces overthrew the Taliban in 2001.

This summer has also been the deadliest period for foreign troops in the country, with the militants launching more daring and deadly attacks.

"Three coalition service members were killed Sept. 29 in southern Afghanistan when their vehicle struck an IED," the U.S. military said in a statement, referring to an improvised explosive device, or roadside bomb.

The U.S. military did not release the nationalities of the soldiers and said the incident was under investigation.

In another incident, a soldier from the NATO-led International Security Assistance Force shot dead a civilian on Monday in Sangin district of southern Helmand province after he failed to stop while approaching a military convoy, ISAF said.

"When he failed to stop and continued to approach, a soldier issued a verbal warning then fired two shots further warning him to back away," ISAF said in a statement.

"He failed to react to either and, fearing a suicide bomber, the soldier then fired one aimed shot that killed the man," it said.

Most ISAF soldiers in Helmand are British. (Writing by Jonathon Burch; Editing by Valerie Lee) ((Kabul newsroom +93 799 335 284))

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