Auditors raised the alarm in 2004 after combing the books to discover officers may have taken advantage of American Express credit cards given to cover expenses while carrying out royal protection duty and other high-profile work.

This week, two senior officers were arrested on charges relating to the alleged abuse.

A spokesman for the Met, which has its books signed off by the Audit Commission, said: 'Auditors looking at use of corporate credit cards discovered there were loose processes or sloppy management in some areas. In some cases it did not appear there were proper controls over the way the cards were being used.'

For more, go to mpa.gov.uk