The Commons authorities have asked police to investigate the leaking of details of MPs' expenses, it was revealed this afternoon.
A spokesman for the House said there were "reasonable grounds to believe a criminal offence may have been committed".
He said: "The House authorities have received advice that there are reasonable grounds to believe a criminal offence may have been committed in relation to the way in which information relating to Members' allowances has been handled.
"A report has been made to the Metropolitan Police, asking them to consider the matter."
The House called in the Yard after the Daily Telegraph published extensive details of MPs' claims between 2004 and 2008.
Officials have been preparing around a million receipts for disclosure this summer after losing a long-running freedom of information battle. However, the newspaper has obtained material that includes addresses - which were due to be redacted by the Commons for security reasons.
Gordon Brown blamed long-standing flaws in the expenses system today as he and Cabinet ministers were hit with a slew of new revelations.
The Prime Minister insisted he had done nothing wrong over payments to his brother for cleaning services and claimed twice for the same plumbing bill.
Also revealed in the receipts was that Justice Secretary Jack Straw over-claimed for his council tax and mortgage bills before realising his mistake and paying the money back.
Other ministers faced questions about lavish spending on their properties and other apparent discrepancies.
Scotland Yard said in a statement: "The Metropolitan Police can confirm we have received a request from the House of Commons to investigate the alleged unauthorised disclosure of information relating to members' allowances.
"We are currently considering their request."