"The case for Turkish membership of the European Union in my view is clearer than ever, for increased economic prosperity, for a bigger market for our goods and services, for more energy security and for real benefits for the EU's long term stability," Cameron said.
"I also believe the accession process itself is a catalyst for change. I will continue to champion Turkey's accession," Cameron added.
Cameron was speaking during a news conference with Turkish Prime Minister Tayyip Erdogan.