David Cameron has called for a cut in the cost of politics following reports that MPs could be in line for a bumper pay rise.
The Independent Parliamentary Standards Authority (Ipsa) is reported to be considering setting a pay rise of around £7,500, taking an MP's salary to £75,000.
But the Prime Minister said he had urged the body to "show restraint" and claimed it would be "unthinkable" to make Westminster more expensive to the taxpayer.
Ipsa, which is charged with regulating MPs' pay and perks, is set to announce the rise on July 11, the Sun on Sunday reported.
Meanwhile the Mail on Sunday quoted a source close to Ed Miliband as saying any rise "has to be seen in the context of the decision to limit public-sector workers' pay increases to 1% and the fact that some private-sector workers have had their pay cut".
The newspaper said sources indicated the regulator would suggest raising MPs' pay to £75,000 a year, in a series of upratings starting in 2015, coupled with much higher pension contributions.
Cameron said he did not know what the independent body would recommend.
But he added: "Whatever Ipsa recommends we can't see the cost of politics or Westminster going up.
"We should see the cost of Westminster go down."
He added: "Anything would be unthinkable unless the cost of politics was frozen and cut, so I'll wait and see what Ipsa have to say.
"What I said to Ipsa was that restraint is necessary."
The Prime Minister's plans to cut costs by reducing the number of MPs by 50 to 600 were ruined when the Liberal Democrats turned against them in a tit-for-tat act after entrenched Tory opposition blocked reform of the Lords.
Cameron said: "I famously had a plan for reducing the House of Commons which was nearly there.
"Actually the House of Commons voted for it. I'm the first Prime Minister who achieved this feat of getting the House of Commons to reduce their number.
"For one reason or another that fell apart."
Matthew Sinclair, chief executive of the TaxPayers' Alliance, said: "MPs are already very well paid both in terms of European politicians and the average salary in this country.
"It would be particularly egregious for politicians to be handed a whopping great pay rise while hard-pressed taxpayers tighten their own belts.
"Ipsa must recognise that its own polling shows the public simply do not support an increase, nor would it be consistent for MPs to take a rise while rightly freezing pay elsewhere in the public sector."