The powerful speaker of the British House of Commons resigned Tuesday because of a backlash over excessive expense claims by lawmakers, marking the first time in three centuries a speaker has been forced out.

Though Michael Martin has not been caught up in recent revelations about lawmakers expenses — reimbursements for chandeliers, moat cleaning and mortgage payments have outraged taxpayers — he was blamed for creating a climate in which such excesses were allowed.

In an extremely short statement to the House of Commons, Martin said he would leave the post June 21 to maintain "unity" in Parliament's lower chamber.

"This will allow the house to proceed to elect a new speaker," Martin said. "This is all I have to say on this matter."

He then moved on to other parliamentary business.

Martin resisted reforms designed to make lawmakers' expenses more transparent and fought to block publication of the expense claims. But lawmakers themselves have been reluctant to expose their sometimes lavish spending, and Martin's defenders said he was taking the fall for their avarice.

The announcement came a day after Martin ignored calls to resign, invoking parliamentary procedure to stall debate on a motion of no-confidence intended to force him out. Lawmakers, normally respectful of the speaker, had to be called to order repeatedly by Martin as he tried to make himself heard.

Martin's replacement will be elected by the 646 lawmakers in the House of Commons the day after he steps down.

The new speaker will take over a position steeped in history and entrusted with the running of the House of Commons. The speaker keeps order during debates, decides which lawmakers are called on to speak and represents the chamber in discussions with Queen Elizabeth II and the House of Lords. The position is not a partisan one, and the speaker is expected to be fully impartial.

The last speaker to be forced from his position was Sir John Trevor, who was found guilty of accepting a bribe in 1695.

Rodney Barker, a professor of government at the London School of Economics, said Martin's departure shows Parliament is taking reform seriously.

"It won't solve anything at all, but if his successor could appear to be taking charge of things in a way that implements proper procedures, probity, and decent use of public money, that would be the very opposite of Michael Martin's position," Barker said. "He has been seen as a supporter of the most greedy and the most mean."

Martin was elected to represent a Glasgow constituency in the House of Commons in 1979 as a member of the Labour Party and became speaker in 2000.