Turkey said it was extending the seismic survey work being carried out by its Oruc Reis ship in a disputed part of the eastern Mediterranean until Nov. 29, a move that could add to tensions in the region.
NATO members Turkey and Greece are locked in a dispute over the extent of their continental shelves and conflicting claims to hydrocarbon resources in the eastern Mediterranean.
The row erupted in August when Turkey sent the Oruc Reis into waters also claimed by Greece and Cyprus.
It had been expected to finish its survey work by Nov. 23, but a Turkish naval maritime notice said on Saturday the vessel would continue work in an area west of Cyprus for six days longer.
Ankara pulled the vessel out in September to allow for diplomacy with Greece, but then sent it back to the area, prompting an angry reaction from Greece, France, and Germany.
President Tayyip Erdogan said Turkey had acted patiently on the eastern Mediterranean issue despite what he called provocations by Greece and Greek Cypriots.
"EU accusations... about our determined research and drilling activities in the eastern Mediterranean to protect Turkey's rights and Turkish Cypriot interests do not reflect history, law and reality," Erdogan said in a speech.
(Reporting by Tuvan Gumrukcu and Ezgi Erkoyun Editing by Mark Potter and Helen Popper)