Speaking to business leaders in Ankara, Mr Cameron said Turkey was vital for the UK's economy, security and diplomacy, and he criticised those who oppose the country joining the European Union, saying they made him "angry".

He said: "Everyone's talking about the BRICs - the fast-growing emerging, economies of Brazil, Russia, India and China. Turkey is Europe's BRIC. And yet we export more to Ireland than we export to Brazil, Russia, India, China and Turkey all combined. No disrespect to our partners in Ireland, but we have to change that."

Mr Cameron, during a speech to Turkey's equivalent of the British chambers of commerce, also called for less protectionism and more Turkish investment in the UK.

He added: "We're encouraging British business to be more ambitious in developing new markets - as Turkish business has done. Vodafone, Tesco and HSBC are just three of the big British investments already in Turkey. I want to see many, many more.

"Today the value of our trade is over nine billion dollars a year. I want us to double this over the next five years. We cannot let the protectionists win. The truth is that trade is the biggest wealth creator we've ever known, and it's the biggest stimulus we can give our economies right now."

Mr Cameron's comments came as he took aim at those creating obstacles to Turkey joining the EU, including France and Germany. Many Tory right-wingers also oppose the idea of a Muslim country becoming a member of the bloc.

He said Turkey had a right to be a member, given its support for Nato, including in Afghanistan.

"I believe it is just wrong to say Turkey can guard the camp but not be allowed to sit inside the tent," he claimed. "So I will remain your strongest possible advocate for EU membership and for greater influence at the top table of European diplomacy."

He likened Turkey's difficulties now to Britain's when former French president Charles de Gaulle sought to block the UK's entry to the EU. "We know what it's like to be shut out of the club," he added.