The defence correspondent for the Sunday Mirror newspaper has been killed in an explosion in Afghanistan, the UK's Ministry of Defence has said.

Rupert Hamer was one of two Mirror journalists embedded with the US Marine Corps when their vehicle hit an improvised bomb near Nawa, in Helmand.

Mr Hamer's colleague, photographer Philip Coburn, is in a serious but stable condition.

A US Marine and an Afghan soldier were also killed in the blast.

Four US Marines were seriously injured.

A former commander of British forces in Afghanistan, Col Richard Kemp, said Mr Hamer had worked very closely with the military.

He said: "You won't hear a bad word said about him. He was extremely well liked and well respected as a journalist, he was fearless in his reporting, he wouldn't let anybody off the hook easily, but he also understood the way the military worked.

"He had great empathy with soldiers in particular on the ground and some of the work he did for the Sunday Mirror without a shadow of a doubt helped improve the lot of the soldier who was fighting in Afghanistan and elsewhere."

Defence Secretary Bob Ainsworth said Mr Hamer and Mr Coburn had accompanied him on his most recent trip to Afghanistan.

"I got to know them well and I was impressed by their hard work and professionalism," he said.

"My thoughts and deepest sympathies are with the families, friends and colleagues of both men at this extremely distressing time."

He added: "As a defence correspondent, Rupert Hamer was in regular contact with press officers at the MoD.

"I know they had great respect for his work and the news of his death has been met with great sadness amongst us all."