ANKARA, Turkey (AP) -- Turkish President Recep Tayyip Erdogan issued a warning Tuesday to Greece, Cyprus and international companies exploring for gas in the eastern Mediterranean not to "step out of line" and encroach on Turkey's rights.
Meanwhile, Greek authorities said a Turkish coast guard vessel rammed a Greek coast guard boat off a couple of uninhabited islets in the Aegean Sea over which the two NATO allies nearly went to war in 1996.
Erdogan made the warning in an address to legislators of his ruling party as Turkish warships continued to impede a rig from reaching a location off Cyprus where Italian energy company Eni is scheduled to drill for gas.
Turkey opposes the drilling, saying it disregards the rights of breakaway Turkish Cypriots. The Cypriot government says it has a sovereign right to drill, and that if the search is successful, any income would be shared equitably if the island is reunified.
The European Union on Monday cautioned Turkey to respect the territory of its member states and to avoid ratcheting up tensions.
Cyprus has been divided since Turkey invaded in 1974, after a failed coup by supporters of union with Greece. The island joined the EU in 2004, but only the southern part enjoys full membership benefits.
Many in Turkey also dispute Greek ownership of uninhabited Aegean islets near Turkey's coastline.
"Opportunistic attempts concerning gas exploration off Cyprus and concerning Aegean islets are not escaping our attentions," Erdogan said. "We are warning those who step out of line with miscalculations in Cyprus and the Aegean.
Greece's coast guard said nobody was injured in the collision around midnight Monday, although the Greek vessel suffered damage to the stern where the Turkish boat hit it with its bows. It says the precise circumstances of the incident are still unclear.
The coast guard vessels were off the uninhabited Imia — Kardak in Turkish — islets, which both countries claim and are prime fishing spots, attracting fishing boats from both countries.
Greek government spokesman Dimitris Tzanakopoulos voiced concern but appealed for restraint.
"Right now there is no need to pour more oil on the flames. What is needed is calm, level-headedness and a serious handling of the situation," he said, commenting on the collision.
"Recently we have been seeing increasingly provocative behaviour from Turkey, which is a source of very serious concern to us," he told private Alpha radio.
Tension around the islets has remained high since the two NATO allies came to the brink of war over them more than 20 years ago, when they deployed their navies to the spot and a Greek helicopter crashed into the sea, killing three crewmen.