Turkey has said that its Oruc Reis exploration vessel will now carry out seismic surveys in a disputed part of the eastern Mediterranean until August 27, in a move likely to stoke tensions in the region.
Turkey and Greece, NATO allies, vehemently disagree over claims to hydrocarbon resources in the area based on conflicting views on the extent of their continental shelves in waters dotted with mostly Greek islands.
Earlier this month, Turkey said the Oruc Reis would conduct seismic exploration until Aug. 23 in waters claimed by Greece, Cyprus and Turkey. Athens and Nicosia have called the survey illegal.
On Sunday, the Turkish navy issued a new advisory saying that the work of the Oruc Reis and two other vessels, the Ataman and Cengiz Han, would continue until Aug. 27.
Seismic surveys are part of preparatory work for potential hydrocarbon exploration.
Turkey and Greece are also at odds over issues such as overflights in the Aegean Sea and the divided island of Cyprus following a Turkish invasion in 1974.
Turkey has also been exploring for hydrocarbon resources in the Black Sea.
On Friday, President Tayyip Erdogan announced the discovery of a 320 billion cubic metre gas field, the largest such find in Turkish history.