The Times has revealed that Gordon Brown will face a revolt over plans to reduce the benefits paid to some of Britain’s poorest families by up to £15 a week.

The new proposals from Labour, which are due to be introduced just before the election, could mean that some people would lose one fifth of their income.

At the moment 300,000 people on low incomes are allowed to keep up to £780 a year of their housing allowance if they can find accommodation that costs less than the maximum benefit.

The Treasury says that the policy is costs too much, and that the right to keep any extra money will be abolished from April 1.  The change would be made only three months after the rate of VAT is increased to 17.5%.

Crisis, the housing charity, said that it could mean that people receiving £65-a-week jobseeker’s allowance would lose 20% of their income.

Former Labour welfare minister Frank Field, who led the protest over the abolition of the 10p rate of income tax, said that he would try to stop the measure being pushed through Parliament.

Karen Buck, a Labour MP who campaigns on housing, said:

“We should not under any circumstances be taking money from the poorest and making them choose between reasonable housing bills and meeting day-to-day expenses. I don’t know how many that applies to. Either way, either the savings aren’t there or poor people will suffer.”

Sarah Teather, the Liberal Democrat housing spokeswoman who discovered the change, said:

“£15 a week may be small change to ministers, but for families struggling to make ends meet it is incredibly important. Gordon Brown has once again abandoned the people who need the most help.”

A spokeswoman for the Department for Work and Pensions said:

“Local housing allowance is aimed at providing the people who need it most with decent accommodation. This small change will not affect our customers’ ability to pay their rent and further support is available to those on a low income to help with other expenses.”