There is "a long way to go" before EU leaders at a special summit in Brussels can agree a long-term budget, Downing Street has said following a meeting between David Cameron and European Council president Herman Van Rompuy.
Mr Cameron was the first of the EU's 27 national leaders to meet summit chairman Mr Van Rompuy and European Commission president Jose Manuel Barroso ahead of what are expected to be marathon negotiations beginning this evening in the Belgian capital.
Arriving in Brussels, the Prime Minister insisted that any rise in European Union spending was "quite wrong" and said he would be fighting "very hard" to secure a good deal for British taxpayers and to keep the rebate negotiated by Margaret Thatcher in the 1980s.
"These are very important negotiations. Clearly at a time when we are making difficult decisions at home over public spending, it would be quite wrong - it is quite wrong - for there to be proposals for this increased extra spending in the EU," he said.
"So we are going to be negotiating very hard for a good deal for Britain's taxpayers, for Europe's taxpayers, and to keep the British rebate."
Mr Cameron is calling for a real-terms freeze, or even a cut, in the budget for 2014/20 - the sole subject on the agenda for the summit which starts tonight and may run into the weekend.
He has welcomed proposals from Mr Van Rompuy which would deliver a small real-terms cut in EU spending commitments, but has made clear he is unhappy with other details of the package, which demands a reduction in the £2.9 billion UK rebate.
After his half-hour meeting with Mr Van Rompuy, a Downing Street spokesman said: "The Prime Minister set out our position that while the latest proposals were a step in the right direction, they did not go far enough and that we think more can be done to rein in spending.
"He also set out the UK's position on the rebate - that it was fully justified and we did not support any changes. It was clear that there was a long way to go before we had a deal that reflected the difficult decisions being taken by member states."
Other EU leaders will be ushered in to see the two presidents throughout the day as part of an unusual pre-summit effort to avoid deadlock when the summit gets under way over dinner.