Welfare for wealthy must be cut first, says Nick Clegg
"Welfare for the wealthy" must be tackled before the government makes any more benefit cuts, Nick Clegg has said.
The deputy prime minister told the BBC there was a problem when low-paid people were being asked to fund winter fuel allowances for those who have retired to warmer countries.
Chancellor George Osborne will announce the details of spending plans for 2015-6 later this month.
Labour said it would cut the allowance for the UK's richest pensioners.
The Department for Work and Pensions has yet to agree its settlement with the Treasury, ahead of the spending review on 26 June.
Mr Clegg told the BBC One's Andrew Marr programme that in order to tackle welfare reform you needed to "start at the top".
"The fact that we're asking people on low incomes to pay through their taxes to basically pay the fuel bills of people who don't need to heat their homes because they live in sunny parts of Europe and maybe didn't even work here before they retired, I think that lifts the lid on a wider problem in our welfare system."
He continued: "I don't think you can have a debate about welfare that is provided to people at the bottom, if you're not prepared to have a debate on the welfare that is provided to people at the top.
"That isn't fair, that is why I will only proceed with further welfare reform if it is done fairly."
Mr Clegg said a debate about welfare for the wealthy was needed.
"This is being blocked at the moment because the Conservatives don't want to have that debate and that is why we can't move forward."
In the coalition agreement, the Conservatives and Lib Dems agreed to protect pensioner benefits like the universal winter fuel allowance until the general election.
But Mr Clegg said, much of the spending review period fell after election day.
The winter fuel allowance has proved controversial because it is paid regardless of income.
A Conservative Party spokesman said: "David Cameron promised to protect the benefits for pensioners who've worked hard and done the right thing - and we've kept that promise.
"Conservatives want to do more to fix the welfare system so that it works for the hard-working people who pay for it."
Winter fuel payments, which are a £100 to £300 tax-free sum, cost the government £2bn a year and all the main parties have acknowledged further cuts will need to be made after the next election in order to reduce the budget deficit.
Speaking earlier this month, shadow chancellor Ed Balls said wealthy pensioners would not be eligible for the winter fuel allowance under a Labour government.
"At a time when the public services that pensioners and others rely on are under strain, it can no longer be a priority to continue paying the winter fuel allowance to the wealthiest pensioners," he said.