The Metropolitan Police are investigating two unnamed MPs over their expenses claims after the parliamentary watchdog IPSA brought cases to the force. The probe comes after the explosive 2009 expenses scandal which rocked Westminster after it emerged that MPs had used public cash to claim for everything from moat cleaning to grapefruit bowls.

Scotland Yard said IPSA referred three claims to the force in March and two are now being examined. "An assessment of the third referral resulted in a 33-year-old woman, an employee of an MP, receiving a caution in April for fraud by false representation," a spokesperson for the Met explained.

The investigation, first reported in The Evening Standard, was revealed in IPSA's annual report which was published on 3 December. Peter Davis, IPSA's compliance officer, said: "During the course of the reporting period I have felt it necessary for the first time during my term of office to refer requests for investigation received from IPSA to the police."

He added: "The compliance officer has a joint working agreement with the Met which states: 'Where, in the exercise of their duties, either IPSA or the compliance officer is given a reason to suspect that a criminal offence may have been committed by an MP or a member of an MP's staff, they shall seek advice from the commissioner and notify the Met of their suspicions, and hand over any relevant documentation upon request.'"