Hundreds of thousands of people in the UK have been in "huge distress and hardship" because of failings in the Department for Work and Pensions, according to the Labour Party.
Rachel Reeves, the shadow work and pensions secretary, slammed the Prime Minister David Cameron for "failing to get to grip" with the DWP after criticism from MPs was levelled at its handling of major welfare reform projects.
"Cameron's failure to get a grip of the chaos within the DWP has led to huge distress and hardship for hundreds of thousands of people and threatens to land taxpayers with a huge bill," Reeves said.
The Labour MP has called for a debate in parliament on 30 June to discuss the issues with the secretary of state for work and pensions Iain Duncan Smith.
The comments come after the cross-party Public Accounts Committee criticised the DWP's implementation of Personal Independence Payment to disabled people.
Margaret Hodge, chair of the group, said the introduction of the flagship welfare reform has been "nothing short of a fiasco".
Personal Independence Payments (PIPs), which replaced the Disability Living Allowance in April 2013, are designed to help people with the extra costs caused by long-term illnesses or disabilities.
Those entitled to the benefit can receive between £21.55 ($36.72, €27.02) and £138 a week from the government.
The same group of MPs also slammed the DWP over the introduction of the government's other flagship welfare reform, Universal Credit, late last year.
The MPs said the programme suffered from "alarmingly weak" management and argued that its implementation has been "extraordinarily poor".
The DWP claimed the scheme, which consolidates six means-tested working-age benefits into a single system, will make the benefits system simpler for claimants.
But the accounts committee argued that the DWP had not developed a comprehensive plan to roll out the programme.
"£425m has been spent so far on the programme," said Hodge.
"It is likely that much of this, including at least £140m worth of IT assets, will now have to be written off."
But a DWP spokesperson said: "The report doesn't take into account our new leadership team, or our progress on delivery. We have already taken comprehensive action including strengthening governance, supplier management and financial controls.
"We don't recognise the write off figure quoted by the committee and expect this to be substantially less. The head of Universal Credit Howard Shiplee has been clear that there is real potential to use much of the existing IT."
Reeves recently announced that the Labour Party would "pause" the Universal Credit programme for three months if elected.
The DWP had not responded to a request for comment at the time of publication regarding the latest comments from Reeves.