The European Union pressed Turkey on Monday to keep its word and extend a customs accord to cover 10 new EU countries, including Cyprus, if it wants to start EU entry talks as planned.

Luxembourg Prime Minister Jean-Claude Juncker, whose country holds the EU's rotating presidency, implied that a refusal by Ankara to sign the accord could call into question October planned start date for EU negotiations.

"Turkey must sign the protocol (extending a customs union signed between the EU and Turkey in Ankara in 1963)," Juncker told reporters after talks with Cypriot President Tassos Papadopoulos.

"There is a general expectation by EU member states that Turkey sign the protocol as soon as possible," he added. "There is no possibility for Ankara to start commenting on what has already been negotiated."

At a tense summit last December, EU leaders agreed to start membership talks with Turkey on October 3 after Prime Minister Recep Tayyip Erdogan agreed to extend the customs accord to all 25 current EU members before that date.

While Turkey insists that extending the customs accord to Cyprus does not amount to official recognition of Cyprus, the EU says it amounts to de facto recognition.

Cyprus has been divided since 1974, when Turkey occupied its northern third following a Greek Cypriot coup seeking to unite the island with Greece.