Turkish President Recep Tayyip Erdogan said that his country's surveying ship Oruc Reis will continue exploration in the Eastern Mediterranean until 23 August.
"We will never bow to banditry on our continental shelf. We will not back down against the language of sanctions and threats," Erdogan added, as quoted by Reuters.
This comes after Greece demanded last week that Turkey "immediately end" its "illegal" drilling operations in the eastern Mediterranean.
Earlier in the day, Greek defence publication Army Voice reported that Turkish submarines have intensified operations off the Greek coast in the Aegean Sea. According to the report, there were spotted between six and eight Turkish submarines in the Aegean and Mediterranean seas.
The two countries saw their relations deteriorating after Turkey announced that its surveying ship Oruc Reis had started seismic exploration activities in a disputed zone of the eastern Mediterranean south of Antalya and west of Cyprus. Ankara was prompted to begin its seismic research in the area after Greece and Egypt had signed a maritime deal on an exclusive economic zone in the eastern Mediterranean. Turkey then criticised the deal, saying that the area of this zone was located on Turkey's continental shelf.