The death of a Royal Marine killed in an explosion in Afghanistan on New Year's Eve marked an end to Britain's worst year of losses since the conflict began.

The serviceman from 45 Commando, based in Arbroath, died as he took part in a routine patrol in the Sangin district of Helmand province yesterday afternoon.

He is the 137th British serviceman to die in Afghanistan since the start of operations in October 2001, and the 12th Royal Marine to die in the past two months.

His death means the number of British personnel killed in Afghanistan last year stands at 51, compared with 42 in 2007 and 39 in 2006.

Between October 2001 and the end of 2005, there were five fatalities.

Commander Paula Rowe, spokeswoman for Task Force Helmand, said: "Every death is tragic, yet at the turning of the year, with the celebration and hope it promises, this loss is all the harder to bear.

"All our thoughts go to his family, friends and colleagues who will be devastated by his sacrifice."

Royal Navy Captain Mark Windsor, spokesman for International Security Assistance Force (Isaf), of which the UK forces are part, said: "Our sincere condolences and deepest sympathies are with the family and friends of this brave serviceman, particularly at this time of year.

"This serviceman's life was taken while helping to bring peace and security to the people of Afghanistan. Isaf will continue to fight for the cause for which he made the ultimate sacrifice."

Next of kin have been informed, the Ministry of Defence said.

The previous British serviceman to die in Afghanistan was also a Royal Marine, 20-year-old Lance Corporal Ben Whatley, who was killed on Christmas Eve.

L/Cpl Whatley, of Tittleshall, Norfolk, was killed by enemy fire in Helmand province while leading his men into action against Taliban fighters, the MoD said.

The Marine, a member of 42 Commando, had been due home on leave on January 8 when his parents were due to hold a belated Christmas celebration.