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By Luke Baker

LONDON, Feb 29 (Reuters) - Britain's Prince Harry flew out of Afghanistan on Friday after news leaked that he had been fighting on the frontline for 10 weeks, defence sources said.

The 23-year-old grandson of Queen Elizabeth and third in line to the throne left Afghanistan prematurely amid fears for his security and for those soldiers fighting alongside him.

He was sent to Afghanistan in December. But for security reasons and in agreement with the Ministry of Defence, the British media did not report the deployment.

That agreement collapsed after Web sites in Australia, Germany and the United States leaked the news on Thursday.

The ministry said the decision to withdraw him was "taken primarily on the basis that the worldwide media coverage of Prince Harry in Afghanistan could impact on the security of those who are deployed there, as well as the risks to him as an individual soldier".

Harry, the son of Prince Charles and the late Princess Diana, has been active during his 10 weeks of combat, calling in air strikes against Taliban positions, carrying out foot patrols and firing a heavy-duty machine gun at suspected fighters.

It is the first time a British royal has been deployed in combat since the Falklands war 25 years ago, when Harry's uncle Prince Andrew flew helicopters.

After his presence became known, there were heightened concerns he could become a target of the Taliban, al Qaeda or other Islamist militants operating in Afghanistan, endangering the prince as well as fellow soldiers.

Afghan Foreign Minister Rangeen Dadfar Spanta hailed Harry's involvement, calling it "a sign of solidarity for Afghans in their anti-terror fight ... it shows that the prince is ready to combat this serious challenge."

MEDIA DEAL

When it was announced last year that he could be deployed to Iraq, militant groups threatened to kidnap or kill him. The deployment was later cancelled. When it came to Afghanistan, the military tried a different approach.

The fact the embargo on the deployment held for 2-1/2 months was a surprise, particularly given the cut-throat, free-for-all nature of the British tabloid press. But it has also led to a debate about the media and "backroom deals".

Jon Snow, a British news reader, said the embargo could be damaging for the media's credibility.

"One wonders whether viewers, readers and listeners will ever want to trust media bosses again," he wrote on his blog.

Reuters, like other news outlets, agreed to the embargo, seeing it as similar to those often arranged with banks and governments to release sensitive information at a specific time.

The only British national newspaper that did not put the Harry story on its front page on Friday was the Independent.

"The most interesting aspect about all this is the breaking of the media embargo by Drudge, but we decided that in itself wasn't big enough to warrant the front page," deputy editor-in-chief Ian Birrell told Reuters.

As far as the embargo goes, though, Birrell was supportive.

"I don't see a problem at all. I think the media has acted in a very responsible manner on what has been a difficult situation in which lives were at risk," he said. (If you want to read more or comment, please see: http://blogs.reuters.com/uknews/2008/02/29/does-this-change-your-opinion-of-prince-harry/ ) (Editing by Myra MacDonald)

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