Michael Martin has told the Commons he will relinquish the office of Speaker on Sunday, June 21, in a move expected to pave the way for a radical reform of parliament.

Speaker Martin's dramatic gesture came just 24 hours after he was publicly humiliated by a string of MPs calling in the Commons for him to quit.

The election of the new speaker will take place on Monday, June 22.

Mr Martin has become the highest-profile victim of the Westminster expenses scandal.

In a statement lasting less than a minute, he told the Commons: "Since I came to this House 30 years ago, I have always felt that the House is at its best when it is united.

"In order that unity can be maintained, I have decided that I will relinquish the office of Speaker on Sunday, June 21.

This will allow the House to proceed to elect a new Speaker on Monday, June 22.

"That is all I have to say on this matter."

Mr Martin's decision almost certainly means a by-election in his Glasgow North East seat, which he fought at the last General Election as Mr Speaker. Traditionally, he would then go to the House of Lords.

Although Mr Martin had a 10,134 majority in 2005 the main opposition parties did not stand against him.