First it was politicians now it's policemen - Abuse of expense claims. Who will be next?

Scotland Yard chiefs have agreed a secret amnesty for more than 1,000 officers and staff who misused corporate credit cards, it has been revealed.

An internal audit discovered 1,183 Metropolitan Police employees broke rules governing the use of American Express charge cards.

Senior officers were so overwhelmed by the number of cases they decided the card holders would not be punished - deciding instead that the staff, the vast majority of whom worked in counter terrorism and other specialist crime inquiries, would be given "training and guidance".

More than 300 people were initially referred to anti-corruption detectives when evidence emerged their claims were potentially fraudulent.

Of these cases, 50 were passed to independent investigators. Three officers have since been convicted of criminal offences and two more await trial.

Jenny Jones, of the Metropolitan Police Authority, said training and guidance is "not enough" and some disciplinary action should be taken. She said: "I find it unacceptable that the police have just let these officers go with guidance. They must have known what they were doing was wrong."

Members of the MPA, the force watchdog, have been told privately how an initial sift of accounts exposed the scale of the problem.

Internal auditors decided 1,183 people who used a card, but did not break the law, should be put to one side and labelled "category B". These cases included those who purchased personal items and later repaid the money or bought equipment that should have been purchased by other means.

Meanwhile, claims found to be "potentially unacceptable", including cases of suspected fraud, were labelled "category A" and passed to anti-corruption detectives. Inquiries into abuse of the credit card system by officers are expected to continue until next March, two and a half years after they first began.

A total of 3,533 officers and staff were issued with the cards and at one point £3.7 million of public money was unaccounted for. The majority of this money has been paid back, but legal action is expected against two officers who owe £82,000 and £1,100.