Shares in UK banks took a knock after the ratings agency Moody's said it is considering downgrading Lloyds Banking, Royal Bank of Scotland and 12 other banks in response to the UK regulator appearing less willing to bail out lenders in the future."The reassessment is not driven by either a deterioration in the financial strength of the banking system or that of the government," said Moody's senior credit officer Elisabeth Rudman."It has been initiated in response to ongoing guidance from the UK authorities (the Bank of England, the Financial Services Authority and the Treasury) that banks that fail in the future should not expect capital injections from the public purse."Other banks that could be downgraded include Bank of Ireland UK and the Co-Operative Bank.The report comes at a time of criticism towards banks, whose lending to small and medium-sized businesses fell short of targets according to latest figures.Shares in Lloyds were among the heaviest fallers in the FTSE 100, though RBS's edged higher.---RG