MPs and staff are reportedly being advised to "change bank PIN numbers" in order to guard against incidents of fraud arising from the leak of Commons allowance claims.
Andrew Walker, director general of resources, has reportedly warned MPs that the expenses claims, complete with lists of transactions, are still in the hands of whomever leaked the data to the press.
"It is possible that the data could be used for purposes which are harmful to the individuals to whom the data relate through exposure to identity theft and fraud," Walker warned, The Times reports.
"The details which may be at risk as a result of the leak include bank and credit card details, personal addresses, the names and details of suppliers you have used, personal account details and details of transactions," he wrote. "If you have made claims for the reimbursement of staff costs, the data will also include details of staff names and their bank account details."
Politicians are being warned to keep a close watch on their bank accounts for fraudulent activity as well as (more puzzlingly) to change "PINs and other access codes".
It's possible to speculate that bank details were included in expenses claims, in order for reimbursement to be made, but quite why ATM PIN numbers on online banking login credentials might have been included is a much greater puzzler. If such data wasn't included in claims then there's no logical reason to change it.
Commons officials have received a promise from The Daily Telegraph, which bought the leaked documents from a confidential source, not to publish confidential financial information.
But that promise isn't binding on the original source of the information, which has exposed many members of Parliament to public scorn over claims on the public purse for household and other living expenses.
The resulting scandal has prompted a decision to officially publish expenses claims in mid-June, giving MPs a two week deadline to remove financially sensitive information from files.
Meanwhile Scotland Yard is reportedly considering a request by Commons official to investigate the leak for possible breaches of criminal law.