Turkey announced plans Tuesday to send oil-and-gas research vessels into disputed waters in the Eastern Mediterranean, raising tension with neighbor Greece and ignoring calls from European nations to avoid the action.
State-run television in Greece said the country's armed forces had been placed on a state of readiness.
Turkish authorities said the research vessel Oruc Reis and two support vessels would carry out operations through Aug. 2 in waters south of the Greek islands of Rhodes, Karpathos and Kastelorizo.
``Turkey has added another notch to its aggressive actions toward Greece, toward Cyprus, and toward the European Union as a whole,'' Greece Prime Minister Kyriakos Mitsotakis said.
NATO allies Greece and Turkey are at odds over drilling rights in the region, with the European Union and the United States increasingly critical of Ankara's plans to expand exploration and drilling operations in the coming weeks into areas Athens claims as its own.
German Foreign Minister Heiko Maas, in Athens on a scheduled visit, urged Turkey to avoid ``provocative actions'' and fully engage in planned talks with the EU.
``We have a very clear position: international law must be respected. Therefore, progress in relations with Turkey can only be achieved if Ankara avoids provocations in the eastern Mediterranean,? Maas said after talks in Athens with his Greek counterpart, Nikos Dendias.
Turkey has accused Greece of trying to exclude it from the benefits of oil and gas finds in the Aegean Sea and Eastern Mediterranean, arguing that sea boundaries for commercial exploitation should be divided between the Greek and Turkish mainland and not include the Greek islands on an equal basis.
Athens rejects the argument as being in clear violation of international law.
In Ankara, Turkish President Recep Tayyip Erdogan said Turkey would press ahead with its efforts to search and drill for hydrocarbons in the Mediterranean.
``We are not subjected to anyone's permission (concerning) our seismic exploration vessels or our drilling vessels,'' Erdogan said in a speech marking the second anniversary of Turkey's transition to a new political system that increased presidential powers.
``Whatever the international maritime laws require, whatever our rights in the eastern Mediterranean are, we have taken our steps within that framework and we will continue to take these steps in the same way.''
Greece is pressing other EU member states to prepare ``crippling sanctions? against Turkey if it proceeds with the oil-and-gas exploration plans detailed in May by Turkey's state-run oil company, TPAO.
EU foreign policy chief Josep Borrell last week said he would launch an initiative to engage Turkey in talks, citing ``worrying developments? in the Eastern Mediterranean and the civil war in Libya.
Germany has already hosted unannounced talks with senior Greek and Turkish officials to try and restart discussions to ease the tension.