Fire Brigades Union general secretary Steve Wright has called on Labour MPs to vote against the government's assault on disabled benefit claimants.
Wright warned that the multi-million-pound cuts would lead to 1980s levels of poverty.
The firefighters' union leader said that cabinet ministers were "gleefully eulogising" about the cutbacks.
Steve Wright, Fire Brigades Union general secretary, said:
The government's drastic cuts to disability and welfare benefits are a Thatcherite assault on the welfare state.
Cutting benefits will cause a surge in food bank use and lead to poverty levels last seen in the 1980s.
Labour in government has a duty to support the poorest and most vulnerable by funding a generous welfare state.
However, cabinet ministers like Liz Kendall and Pat McFadden are gleefully eulogising in broadcast interviews about the need to cut the derisory payments made to the disabled and vulnerable.
It's shameful that a Labour government should adopt that Thatcherite approach.
Backbench Labour MPs must oppose these cuts and demand that ministers introduce a wealth tax to fund public services and pay.
The Fire Brigades Union stands in solidarity with disability benefit claimants and other vulnerable people who will suffer from these cuts."
