The men, who were from the Royal Logistic Corps (RLC) and were attached to 1st Battalion The Royal Welsh Battlegroup, died due to an indirect fire attack in the northern part of Nahr-e Saraj district.
The thoughts and condolences of everyone serving in the Combined Force are with their families and friends, said Major Ian Lawrence, a spokesman for Task Force Helmand.
The identities of the men have not been disclosed, but their families have been notified, MoD added
BBC noted that a total of 412 British soldiers have died in Afghanistan since the war began in October 2001.
The British government announced in late March that 500 British troops will depart Afghanistan this year, leaving 9,000 still in Helmand at the start of 2012. Britain will then pull out 1,500 troops next year before accelerating its withdrawal at the beginning of 2014.