Britain's Prime Minister Tony Blairlaughs with supporters as he arrives at Trimdon Constituency Labour Club in Trimdon, northeast England, yesterday. - REUTERS

TRIMDON, England, (Reuters):

Tony Blair announced yesterday he would step down on June 27 after a decade as prime minister, and told Britons disillusioned by the war in Iraq that he had always done what he believed was right.

Blair's popularity has suffered since he sent British forces to join the 2003 U.S-led invasion of Iraq. A Labour Party rebellion in September forced him to say he would quit within a year, opening the way for Gordon Brown to take over.

"Hand on heart, I did what I thought was right," Blair told Labour Party members in his constituency in northern England. "I may have been wrong, that's your call. But believe one thing, if nothing else: I did what I thought was right for our country."

Brown the favourite

Blair's resignation triggers a contest to lead the Labour Party that Finance Minister Brown is favourite to win. Labour said its new leader and deputy would be announced on June 24.

The new party leader would become Prime Minister after the departure of Blair, the only person in a century besides Margaret Thatcher to have held the post for 10 years.

"I think that's long enough, not only for me, but also for the country, and sometimes the only way you conquer the pull of power is to set it down," Blair said.