Tensions have risen in the eastern Mediterranean with an escalating war of words between Athens, Ankara and Nicosia over oil and gas reserves in the region.

Wrangling over hydrocarbons to be found in the area’s waters, has intensified after the leaders of Greece, Cyprus and Egypt signed an agreement in Cairo on Saturday to boost energy cooperation.

Within minutes of the accord being announced Cyprus’s president, Nicos Anastasiades, accused Turkey of “provocative actions” for sending a surveillance vessel and war ships to search for natural resources in the island’s exclusive economic zone.

“Turkey’s provocative actions do not just compromise the peace talks,” he said, referring to UN-brokered reunification negotiations suspended by his government last month. “[They] also affect security in the eastern Mediterranean region.”

Talks aimed at reuniting Greek and Turkish Cypriots were restarted earlier this year after a 10-year hiatus amid expectation that the under-sea reserves would facilitate resolution of the west’s longest-running diplomatic dispute.

With pipelines to be built through Turkey – by far the cheapest and most effective way of transferring the oil and gas to Europe – seasoned Cyprus watchers spoke of a potential game-changer. In May, the US vice-president, Joe Biden, underscored those hopes with the first visit to the island by a senior US official in almost 50 years.

But instead of galvanising the feuding communities to conciliate, the prospect of finding alternative energy supplies appears to have widened the gulf between them.

Turkey’s decision to dispatch a research vessel into disputed waters last month not only resulted in talks being broken off but has exacerbated the row over drilling rights.

On Sunday the head of the Turkish navy, Admiral Bülent Bostanoğlu, revealed he had been handed new rules of engagement in the event of “a situation” involving hydrocarbons in the eastern Mediterranean. “We will move according to the rules of engagement that have been given us,” he said when asked how Turkey’s navy would react if it encountered a Greek or Israeli ship in the region.

On Monday, a senior Greek military official was quoted in the daily paper To Vima as saying: “We have rules of engagement, too, that have been approved by the prime minister and the cabinet, not only just in the Aegean but the south-east Mediterranean for the defence of our national interests.”

Although the breakaway Turkish Republic of Northern Cyprus is unrecognised internationally, Ankara, its mainstay of financial and moral support,insists the statelet should also be participating in the exploration drive.

Raising the alarm during a recent visit to Athens, the island’s newly appointed UN representative, Espen Bard Elder, appealed for calm. “What’s happening right now is actually quite dangerous and I encourage everyone to do their best to avoid any kind of further escalation,” he said.

But the region’s shifting alliances – symbolised by the accord signed in Cairo on Saturday – is unlikely to placate Turkey, already unnerved by events on its eastern front involving Islamic State (Isis).

The agreement was arrived at days after Israel stepped up security cooperation with Cyprus. After the discovery of its own vast reserves, Tel Aviv desperately needs safe export routes through pipelines that go via the island.

Visiting Nicosia last week the Israeli foreign minister, Avigdor Lieberman, lambasted Turkey for intruding on Cyprus’s exclusive economic zone – criticism echoed by the Greek prime minister, Antonis Samaras, when he too held talks in the capital on Friday.

Ankara, which sees itself as the region’s burgeoning economic powerhouse, has signalled that it will respond in kind. Before a visit to the Turkish capital by the US vice-president later this month, it has conveyed its displeasure at the signing of the Cairo accord.

“Tension is definitely on the rise,” said Hubert Faussmann, associate professor of history and political science at the University of Nicosia. “The peace talks have become a victim of the hydrocarbons which are inseparably linked to the Cyprus problem. They have escalated rather than de-escalated the situation,” he told the Guardian from Nicosia.