Botched reforms designed to curb Britain’s benefit bill are set to cost the government a whopping £1.25 billion, Labour warned yesterday.

Ministers had claimed that one million benefit claimants would be on the new universal credit system by the end of this year, but so far only 12,000 have made the transition.

The means-tested credit is due to replace benefits including income support, housing benefit and child tax credits.

The programme has been slammed by welfare campaigners for pushing disabled people into work, moving recipients from a weekly to a monthly income and arbitrary caps on payments.

But now it has emerged that ministers have failed to account for cold-weather payments, free school meals and free groceries that may be distributed alongside the new benefit in their sums.

Labour shadow work and pensions secretary Rachel Reeves said: “The failure of government ministers to decide how universal credit will work with free school meals and cold-weather payments threatens to cost taxpayers £1.25 bn.

“Sadly this is another example of how the government has completely lost control of universal credit. Millions of pounds of taxpayers’ money has been written off.

“Iain Duncan Smith promised one million people would be on universal credit this year but there are fewer than 12,000 on the new benefit. Yet ministers continue to claim that universal credit is ‘on time and on budget’.”

Ms Reeves has voiced her complaints on universal credit in a letter to privileged Tory PM David Cameron.