David Cameron has insisted Britain must make Europe "work for us" as he again ruled out holding an "in out" referendum.
During Prime Minister's questions he was urged to listen to the calls of Conservative eurosceptics who want a swift vote on the UK's relationship with the EU.
However Mr Cameron, who is meeting president of the European Council Herman Van Rompuy on Wednesday, insisted there is "no case" for a vote.
Mr Cameron said: "I want us to be influential in Europe about the things that matter to our national interest - promoting the single market, pushing forward for growth, making sure we get lower energy prices.
"Those are things we will be fighting for but I don't see the case for an in out referendum on Europe. We are in Europe, we have got to make it work for us."
It comes as a group made up from around 80 new intake Conservative MPs plans to press the Government for significant changes in Britain's role in Europe.
Tory MP George Eustice, one of the group's conveners, insisted the initial aim was for reforms rather than a referendum. He said: "The aim of this new group is to promote debate about creating a new relationship with the EU and reversing the process of EU integration."
The group will work closely with think-tank Open Europe and could eventually expand to take in Labour eurosceptics and possibly some Liberal Democrats.
UK Independence Party leader Nigel Farage said: "The Prime Minster has said today that he didn't see the case for an in/out referendum on Europe. 'We are in Europe', he told us and 'we have got to make it work for us'.
"Well it is obvious that the EU is not working for us, and hasn't worked for us. So then what does Mr Cameron propose? By ruling out a referendum he leaves himself naked in the negotiations. Our EU colleagues must be laughing at his naivety."