The rhythm and outcome of accession talks was closely related with Turkey's fulfilling required reforms, Rehn said in a conference in the French capital of Paris.
Rehn also thanked France, who holds the rotating presidency of the union, for its efforts to keep the regular momentum of full membership negotiations with Turkey, in the conference.
Rehn stressed the Turkey's strategic and diplomatic role, and said that Turkey, with an overwhelmingly Muslim population, democratic and secular model and diplomacy, was a significant actor in its region and an important element of stability.
The commissioner also referred to Turkey's role as a mediator in Israeli-Palestine and Israeli-Syrian disputes and Caucasus crisis, and its new policy towards Armenia.
Rehn said the policies of Turkey, including being a mediator in Israeli-Palestine and Israeli-Syrian disputes and Caucasus crisis, and its new policy towards Armenia were the revealings of its key role in the region.
The commissioner also said that Turkey was sending troops to peace operations of Europe, and contributing to EU's fight against terrorism, drug and human trafficking.
Turkey was actively contributing to security of EU citizens, he said adding that Turkey was offering significant trade perspectives in EU member states with its economical potential.
The commissioner also said that Turkey had a key role in ensuring the security of energy routes towards the EU, and verifying those routes.
Turkey became an EU candidate country in December 1999. The union launched accession talks with Turkey on Oct. 3, 2005.