Problems with Gordon Brown's flagship tax credits system are due to "sociological incompetence", the UK's most senior public spending watchdog has claimed.
Sir John Bourne, head of the National Audit Office (NAO), said the chancellor's frequent policy changes are to blame for the "unacceptably high" losses to tax credit fraud and overpayment errors.
Speaking to 'The Sunday Telegraph', he said: "If you constantly alter the system, you increase error and fraud. You foster chaos and confusion as claimants and civil servants try to cope with changes that are not thought through."
In what the newspaper described as a "blistering attack" on the chancellor, Sir John went on to criticise the practice of overpaying claimants with the premise that the government will ask for the money back.
"The thing a...