Benefit overpayments had reached almost Pounds 2.5bn during Labour's time in power, and an overcomplicated system had led to "shocking" levels of error, the Conservatives said yesterday.

The Department for Work and Pensions revealed in answers to parliamentary questions from David Ruffley, the Conservative spokesman for welfare reform, that overpayment of income support caused by officials' errors had reached Pounds 1.17bn since 1997 and pension credit overpayment Pounds 540m.

Income support overpayments were one and a half times higher than in 1997-98 and pensions credit overpayment had trebled in the past three years.

Together with Pounds 910m excess paid in jobseekers allowance, the overpayment was almost Pounds 2.5bn, said Mr Ruffley, blaming the problem on an overcomplicated system.

James Plaskitt, minister for benefits, said an error taskforce had been set up to look at how mistakes made by officials administering benefits could be reduced.