Prime Minister David Cameron on Friday 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 last night said that Britain had "voluntarily put itself in the margins".
But at a press conference at the conclusion of the summit, 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.
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."
Asked whether he agreed with Cabinet colleagues, including Education Secretary Michael Gove, that Britain could survive outside the EU, Cameron said: "It's not a question of whether Britain could survive. The point is what is in our national interest.
"I've always been clear that leaving the European Union is not in our national interests. Why? Well, chiefly because we are a trading nation. We need Europe's markets to be open.
"The EU accounts for around 50% of our trade. Having these markets open means that we don't just want to be able to trade, we want a say in the rules about how that trade works. That's exactly what our EU membership gives us."
Cameron restated his belief that the current negotiations over the future of the eurozone will produce an opportunity for a "fresh settlement" between the UK and Europe, requiring "fresh consent" from the British people - possibly in the form of a referendum.