Three of the European Union's big four states on Saturday demanded a freeze in the EU budget, saying Brussels could not carry on spending more money as countries fight to sort their finances out.

Britain, France and Germany, backed up by Finland and the Netherlands, told European Commission president Jose Manuel Barroso there should be a real terms freeze at 2013 levels, as the EU next year begins negotiations for the 2014-2020 period.

The letter, signed by British Prime Minister David Cameron, German Chancellor Angela Merkel and French President Nicolas Sarkozy, along with Dutch Prime Minister Mark Rutte and his Finnish counterpart Mari Kiviniemi, was released here by Cameron's Downing Street office.

The leaders said the next EU spending round would come as states in the 27-member bloc made "extraordinary efforts to clean up public finances", bringing down debts and deficits to a sustainable level.

The EU finances "cannot be exempt" from such attempts to bring public spending "under control".

"Consistent with this, the commitment appropriations over the next multiannual financial framework should not exceed the 2013 level with a growth rate below the rate of inflation," the letter said, meaning a real terms freeze.

"It is possible to implement ambitious European policies for our citizens if we have a stable volume of spending," the leaders said.

"This calls for a better use of available funds. The challenge for the European Union in the coming years will not be to spend more, but to spend better."