The Work and Pensions Secretary, Iain Duncan Smith, has said that the so-called 'bedroom tax' is "proving a success" as it highlights the mess in social housing left by Labour.
During an exchange with shadow home secretary, Liam Byrne, he said they should commit to reversing a cut in housing benefit for council tenants with a spare room or "stop moaning about it".
He also said Labour "left a shambles", resulting in people in overcrowded accommodation.
"They are having to suffer whilst we subsidise to nearly a billion pounds people to live in houses with spare rooms", he added.
Mr Byrne accused Mr Duncan Smith of "living on a different planet" if he thought the policy had been a success.
"When are you going to realise that this costs more than it saves and this Government should be taxing mansions and not bedrooms?", he said.