However, Turkey has hit back by defending its decision to send a military vessel to accompany its civilian ship – and said it reserved the right to self-defence. An advisory issued by the Turkish navy said the Oruc Reis vessel would operate in a disputed area of the east Mediterranean over the next fortnight.
Yesterday Greek military observers claimed ships from the Turkish Navy’s fleet had left the port of Aksaz, possibly to assist the research ship.
The two countries are in dispute over competing claims for hydrocarbon resources in the region.
Another advisory, known as a Navtex, last month prompted a dispute which was only calmed after German Chancellor Angela Merkel interved, with Turkey agreeing to pause the operation.
Mr Erdogan said on Friday Turkey had resumed energy exploration work in the region – accusing Greece of not keeping its promises on the issue.
Greece spelled out its position in a strongly worded Government statement issued yesterday.
A spokesman said: “Turkey’s new illegal Navtex for illegal surveys south of the island of Megisti on the Greek continental shelf, in combination with the broad mobility by Turkish naval units that has been observed, constitutes a new serious escalation and clearly exposes Turkey’s role which is destabilising and threatening to peace.
JUST IN: Varadkar humiliated – expert exposes how Boris FORCED climbdown
“On the contrary, Turkey is showing in practice that statements referring to its alleged readiness to enter into a dialogue are nothing but a mere pretext.
“Pointing to the signing of the entirely legal Greek-Egyptian EEZ Agreement, Turkey has abandoned dialogue before it was even launched and is resorting to practices of past centuries, employing futile tactics in its effort to create faits accomplis.
“Greece will not be blackmailed. It will defend its sovereignty and its sovereign rights.
“We call on Turkey to immediately cease its illegal activities, which undermine peace and security in the region.”
A statement subsequently issued by the Turkish Government said: “Our military presence in the region is not aimed at increasing tensions.
“It is about resorting to legitimate defence if necessary.
“We will not allow in any way a military intervention against our civilian ship.”
The NAVTEX, issued by the Turkish navy’s office of navigation, covered an area of sea south of Turkey’s Antalya and west of Cyprus.
Mr Erdogan’s announcement comes after Egypt and Greece signed an accord last week designating an exclusive economic zone between the two nations in the east Mediterranean.
Greek diplomats said the deal nullified a similar accord reached last year between Turkey and the internationally recognised government of Libya – but Mr Erdogan has insisted Turkey would maintain its agreement with Libya “decisively”.
Turkey and Greece have a longstanding history of emnity, with Turkey invading northern Cyprus in 1974, with the result that 200,000 Greek Cypriots were expelled from the region.
(Additional reporting by Maria Ortega)