Prince Harry has been secretly serving in Afghanistan with British troops since December, the UK Ministry of Defence (MoD) said overnight.

The MoD made the announcement after several media organisations, including Australia's New Idea magazine, broke an agreement not to publish the story.

Harry, 23, was deployed to Helmand, a dangerous region of southern Afghanistan, in December, seven months after plans to send him to Iraq were scrapped following threats from Iraqi militants to kidnap or kill him.

The army posted him to Afghanistan only after the British and selected members of the international media agreed not to report his presence until he had returned from a scheduled four to six-month deployment.

That embargo was broken overnight when a German newspaper, an American website and an Australian magazine ran the story.

Harry, third in line to the British throne and an officer in the Household Cavalry, has been working as a forward air controller helping coordinating air support and general aviation.

He has also conducted foot patrols through villages and fired on suspected enemy combatants, pool photographs and footage have shown.

The prince has already spent two months there and may be there for four months or more.

He says he is glad he is finally on the front line.

"A bit of excitement, a bit of, phew, finally get the chance to actually do the soldiering that I've wanted to do ever since I joined really, so a bit of everything I think," he said.

Pre-prepared interviews with the prince revealed he joked about his nickname - "bullet magnet" - with Gurkha colleagues.

As a second lieutenant, he has been receiving the same treatment as any other officer, living and working in a heavily-fortified army base in Helmand province.

In recent days, the prince has given interviews to reporters sent out to cover his deployment as part of a "pool" arrangement. He said he was aware that if his presence there was reported it could make him a target for Al Qaeda or others.

"Once this film comes out there'll probably be every single person, every single person that supports them will be trying to slot me," he said.

"Now that you come to think about it it's quite worrying.

"I think there's a lot of guys here who hopefully won't be targeted, but as I say, now that this film has been made and now ... people will know I'm out here, no doubt I'll be a top target."

The head of the British Army, General Richard Dannatt, issued a statement expressing his disappointment that the press embargo - a rare agreement in Britain's usually free-for-all media environment - had been broken by foreign websites.

"In deciding to deploy him to Afghanistan, it was my judgment that with an understanding with the media not to broadcast his whereabouts, the risk in doing (so) was manageable," Gen Dannatt said.

"Now that the story is in the public domain, the chief of staff and I will take advice from the operational commanders about whether his deployment can continue.

"I now appeal to the media to restrain from attempting to report Prince Harry's every move and return to our understanding."

Gen Dannatt, whose decision it was to cancel Harry's deployment to Iraq, said he had been a model soldier.

"His conduct on operations in Afghanistan has been exemplary," he said. "He has been fully involved in operations and has run the same risks as everyone else."

-ABC/Reuters