The soldiers from Task Force Maysan died from injuries sustained in an incident in Al Amarah early this morning, a spokesman said.
He said: "We can confirm that three soldiers have died from injuries sustained in hostile action."
An MoD spokesman said the Task Force had been operating in southern Iraq for "several months". He said: "We think it was a roadside bomb."
He added that further details would not be released until the next of kin had been informed.
Task Force Maysan is a battle group based on the 1st Battalion Staffordshire Regiment and supporting troops. The force is based at Camp Abu Naji, just outside Al Amarah - which has a population of about 300,000 and was the scene of explosive violence last year.
The Staffords are reinforced by a squadron of Challenger 2s from The King's Royal Hussars, No 1 Company, Coldstream Guards and a company from the 1st Battalion, The Royal Regiment of Wales.
The Task Force operates in an area that is about the size of Wales.Reuse content