Britain's Sunday Mirror defense journalist Rupert Hamer has been killed in an explosion in southern Afghanistan, the Ministry of Defense said in London on Sunday.

The 39-year-old Hamer was the first British journalist to die in the Afghanistan conflict. He was blown up Saturday by a roadside bomb as he accompanied U.S. Marines patrolling near Nawa, southern Afghanistan, the ministry said.

Philip Coburn, 43, a photographer also with Sunday Mirror working alongside Hamer, was injured in the explosion, the ministry said, he was "in a serious but stable condition."

A U.S. marine was also killed in the blast and five marines were seriously injured.

British Prime Minister Gordon Brown said that he was "deeply saddened by this tragic news." "My heartfelt thoughts and sympathies are with the families, friends and colleagues of Rupert and Philip."

Hamer was the second foreign journalist to be killed in Afghanistan in the space of 10 days. The other was the 34-year-old Michelle Lang, a female journalist with Canada's Calgary Herald newspaper, who was killed in Kandahar province in southern Afghanistan alongside four soldiers when a roadside bomb exploded beneath their armored vehicle on Dec. 30 last year.

Hamer and Coburn flew to Afghanistan on New Year's Eve for a month-long assignment. They worked as defense journalists in Iraq.

A total of 1,576 troops in the military coalition including 246 British soldiers have died in Afghanistan since the war started in 2001. In 2009 alone, 109 British soldiers were killed in that country.