ATHENS — Greece said Thursday that neighbor Turkey has so far refused to take action requested by the European Union to avoid sanctions from the bloc. 

Government spokesman Stelios Petsas said ongoing Turkish offshore gas exploration in the eastern Mediterranean has undermined efforts to restart talks on a longstanding sea boundary dispute, which has escalated military tension between the two NATO members and regional rivals. 

"Europe is not naive," Petsas said Thursday. "Turkey received the opportunity and the time to change course. It chose not to do so." 

EU leaders on Dec. 10-11 will meet to discuss a range of issues, including external relations and the ongoing dispute between Turkey and EU member states Greece and Cyprus. 

Athens says a warship-escorted survey ship that Turkey has sent into waters between the three countries is operating in areas where Greece has offshore exploitation rights. Greece sent its own naval vessels to monitor the Turkish ships' movements. Cyprus is also angry with Turkish offshore prospecting and drilling in waters round the island where Nicosia claims exclusive economic rights.

Ankara says it has every right to engage in its activities.

On Oct. 1, EU leaders said they would consider sanctions at the December meeting "in case of renewed unilateral actions or provocations in breach of international law." 

Turkey argues that the EU has unfairly sided with Greece and Cyprus in the dispute. A senior aide to Turkish President Recep Tayyip Erdogan met with top EU officials in Brussels last week, maintaining that his government remained willing to restart talks with Greece.