Coalition ministers have traded blows over pensioners' benefits after Iain Duncan Smith urged the wealthy to hand the money back.
The Work and Pensions Secretary said he would "encourage" people to forego perks such as free TV licences and winter fuel payments.
But Deputy Prime Minister Nick Clegg responded by attacking the Tories for blocking means-testing of the benefits.
Mr Duncan Smith's Conservative Cabinet colleague Ken Clarke said he did not believe it was even possible to return money to the Government.
David Cameron has stood by his general election pledge to protect universal benefits for pensioners until at least 2015, despite the coalition's austerity drive.
But in an interview with the Sunday Telegraph, Mr Duncan Smith repeated his view that wealthy pensioners should consider repaying the money. "It is up to them if they don't want it to hand it back," he said. "I would encourage everybody who reads the Telegraph and doesn't need it to hand it back."
Interviewed on the BBC's Sunday Politics, Liberal Democrat leader Mr Clegg said: "I have always argued for us to change the system. I do not think it is reasonable for us to say to a working family who has just had their child benefit taken away... why should they through their taxes pay for the multi-millionaire pensioner next door for his TV licence or his winter fuel payment? I think we should grasp this nettle just as we have grasped other nettles in government. The Conservatives don't want to do so."
Asked about Mr Duncan Smith's comments, Mr Clegg said: "I think the idea of saying in the meantime, you give people benefits and then you say, 'Oh, by the way, can you please give them back?' - I don't think that makes sense. Let's be clear about this. When money is tight, you have to have the right priorities in tough times."
Mr Clarke, 72, refused to say whether he personally returned the universal benefits he is entitled to. "It is certainly the case when it comes to a bus pass and when it comes to the winter fuel all taxpayers should decide and recipients should decide what to do with it themselves," he told the Murnaghan programme on Sky News.
"You can't hand it back to the Government. I don't think it is a system for doing that. Every pensioner and retired person like myself has to make up their own mind about whether they really need it and whether they are going to give it to some worthwhile cause. No doubt most pensioners who are reasonably prosperous give quite a lot of money to charity and worthwhile causes in any event."