UK parliament Speaker to step down on June 21

LONDON May 19 (Reuters) - The Speaker of Britain's lower house of parliament said on Tuesday he will step down in June after criticism of his handling of a scandal over lawmakers' expenses.

"In order that unity can be maintained, I have decided that I will relinquish the office of speaker on Sunday, June 21," Michael Martin told parliament. A new Speaker will be elected the following day, he said.

Martin, the first Speaker to be ousted in more than 300 years, is the most senior casualty of a row over legislators' expenses that has triggered public outrage across Britain and opposition calls for an early general election. (Reporting by Adrian Croft; Editing by Frank Prenesti)