Universal Credit could have potentially “disastrous” consequences for disabled people, a cross-party group of MPs has warned.

The Commons Work and Pensions Committee called on the Government to take urgent action to avoid vulnerable people being forced into “miserable hardship”.

It accused the Department for Work and Pensions (DWP) of making a “serious error” in removing disability premiums – worth up to £64 a week to help pay for the additional costs of living with a disability – under Universal Credit.

Existing claimants who already receive the premiums will be protected under a process called “managed migration”, but the top-ups will not be available to new claimants, the MPs said.

Removing this “vital additional support” could leave disabled people living more isolated lives, relying on unpaid care – including from their own children – or being unable to complete basic daily tasks, they warned.

A report by the committee said that while the DWP had argued “severely disabled” claimants would get more in benefits under Universal Credit, lesser disabled people could be left “substantially worse off”.

It warned that 100,000 families with a disabled child would receive less money under the new system.

“The consequences – for claimants unable to make up the shortfall, and for local services that need to step in and support them – could be disastrous,” it said.

Chairman of the committee Frank Field said: “The Government’s plans will see ‘very’ disabled people getting the extra help they need at the cost of other disabled people.

“We have already seen the terrible cost of the department’s failure to find out what is happening to the most vulnerable claimants in the transition to Universal Credit.

“People receiving the disability premiums are already, by definition, managing in some of the most difficult circumstances imaginable in our society, and this includes disabled children, and children forced to care for a disabled parent.

“It would be a terrible betrayal of these people to allow another failure of planning in this mega reform to worsen their situations, even one bit.

“No-one should ever be forced further into poverty, deprivation, miserable hardship by a policy reform. The Government must assure disabled people across this country that will not happen to them, and plan and put the measures in place to make that promise good.”

The report recommends a range of measures, including urging the DWP to carry out an assessment of the impact of removing the disability premiums for new claimants, and the possibility of introducing a “self-care” payment.

A spokeswoman for the DWP said: “More than a million disabled people will be better off by £100 a month under Universal Credit and £3 billion of funding will help protect families as they move over from the old system.

“Universal Credit does work for the vast majority, and the Managed Migration regulations are set to be debated in Parliament in due course.”

A DWP spokesman added: “We’re committed to ensuring that people get the support they’re entitled to, which is why we’re undertaking these administrative exercises carefully and thoroughly.

“We are making improvements so the PIP process works better for people and to ensure they get the right decision, first time round.

“Under PIP 31% of people get the highest level of support, compared with 15% under its outdated predecessor DLA.”