Prime Minister David Cameron denied that Britain was failing to "pull its weight" in Europe, amid claims that the UK was marginalised by its refusal to get involved in reforms to shore up the ailing single currency.
This week's summit of the European Council in Brussels has been dominated by proposals for economic and monetary union within the eurozone and some EU figures have suggested that the UK has been pushed to the sidelines in discussions.
Finland's Europe minister Alex Stubb said that Britain had "voluntarily put itself in the margins".
But at a press conference at the conclusion of the summit, Mr Cameron insisted that Britain remained "a very, very important and influential player" and was a driving force behind many of the measures agreed over the past two days.
He confirmed that he will not attend a ceremony to present the Nobel Peace Prize to the EU, and suggested that the award should be accepted by a delegation of schoolchildren from each member state.
Mr Cameron said: "I don't accept this idea that somehow Britain doesn't pull its weight in the EU. We are actually a very, very important and influential player and if you look at the text of today's conclusions, so much of it is actually about what Britain wants on the single market and deregulation."
He added: "We are a very active and strong participant in the European Union. Yes, we are a country that is sceptical about further political union in the EU - there are some powers we would like to have back. We are realists about the EU, we have a sort of realistic, gritty debate. That is what we are like as a people and I think that's a thoroughly good thing.
"But when you ask yourself who actually is pulling the weight in Europe, getting things done, which other countries are piling on the pressure on Iran and making sure everyone follows with that, Britain is right there in the vanguard."
Mr Cameron was speaking after EU leaders agreed on the first stage towards a comprehensive banking union within the eurozone.
A "banking supervisor" for the 17-nation single currency is expected to be in place some time next year, under the control of the European Central Bank and with a remit to oversee the solvency of all 6,000 eurozone banks. The Prime Minister said yesterday that he supported the plan, which does not affect UK banks, as long as the "integrity" of the EU's 27-nation single market was not compromised.