French President Jacques Chirac has called on Turkey to clarify its stance on Cyprus and said Ankara must give assurances on its commitments to the European Union.
Turkey is due to start EU entry talks on October 3rd, but it has angered the EU by saying its signing of a key EU protocol does not signify recognition of the Greek Cypriot government.
Ankara backs breakaway Turkish Cypriots in northern Cyprus.
"Following its unilateral declaration on Cyprus, Turkey must make clarifications and assure the 25-nation EU of its willingness to fully respect its commitments (to the EU)," Mr Chirac told a conference of French ambassadors.
"The opening of negotiations with Turkey is just the start of a long and difficult path whose end is uncertain," he said.
Turkey cleared the last obstacle to the talks last month by signing what is known as the Ankara protocol extending its customs union to the 10 new EU members, including Cyprus.
But Ankara also issued a declaration making clear the signing of the protocol did not signify recognition of the Greek Cypriot government, regarded by Brussels as the sole legitimate authority on the island.
Mr Chirac said today that Ankara's declaration posed political and legal problems and was not in the spirit expected of a country hoping to join the EU.
But the European Commission has declared that Turkey's recognition of Cyprus was not legally necessary, though it would help its bid.
Turkey's entry bid faces strong public opposition in some EU member states, notably France, although Mr Chirac backed the EU's decision last December to invite Turkey to entry talks.