LONDON — Prince Harry has become the first member of the royal family in 25 years to serve on the front line after it was disclosed yesterday that he has been fighting the Taliban in Afghanistan.

The 23-year-old prince, who is third in line to the throne, has spent the past 10 weeks with the lives of British troops in his hands in his key role as a battlefield air controller.

He has been operating only 500 yards from enemy positions, calling in airstrikes and carrying out surveillance of Taliban fighters in Helmand province. His military base has come under mortar and machine gun attack five times every day.

In the heat of battle, it has been Harry, an officer in the Household Cavalry, who would give final clearance for airstrikes on Taliban targets. Three British troops have been killed since he arrived in the war zone.

Prime Minister Brown and General Richard Dannatt, the chief of the General Staff, led the tributes to the prince, whom they described as an “exemplary” soldier.

However, news of his deployment ignited a diplomatic row, as General Dannatt condemned Australian, German, and American Web sites for exposing the prince’s secret role.

The British press, in conjunction with Clarence House and the Ministry of Defense, had agreed not to report anything, for the prince’s protection, until he had safely returned.

But with his cover blown, a decision will be taken Friday on whether to withdraw the prince six weeks early. There are fears he could become a prime target for the Taliban now that they know he is fighting against them, which would also endanger the lives of his comrades.

Even when he is back in Britain, the prince’s personal protection will have to be reviewed, as he concedes Al Qaeda terrorists will now be looking to assassinate him.

General Dannatt said: “I am very disappointed that foreign Web sites have decided to run this story without consulting us. This is in stark contrast to the highly responsible attitude of the whole of the U.K. print and broadcast media.”

The officer was full of praise for Harry’s service on the front line. The last member of the royal family to take part in a war was the duke of York, who flew helicopters for the Royal Navy during the Falklands conflict in 1982.

“What the last two months have shown is that it is perfectly possible for Prince Harry to be employed just the same as other army officers of his rank and experience. His conduct on operations in Afghanistan has been exemplary,” General Dannatt. “He has been fully involved in operations and has run the same risks as everyone else in his battle group. In common with all of his generation in the army today, he is a credit to the nation.”

The prince had been posted to Afghanistan to work at a remote British desert outpost in the south of the province, close to the Pakistan border.