Turkey’s oil and gas exploration vessel, Oruc Reis, has arrived in the waters above the continental shelf of Greece near Kastellorizo, Turkey’s Energy and Natural Resources Minister, Fatih Donmez, said on Monday.

The announcement came after Turkey issued a Navtex, or international maritime safety message, early Monday stating the Oruc Reis and two auxiliary ships would be conducting seismic exploration in the area until August 23.

In response, Greece’s Foreign Ministry said the Navtex, “combined with the observed broad mobilisation of units of the Turkish Navy, constitutes a new serious escalation” and is ‘illegal.’

“Greece will not accept any blackmail. It will defend its sovereignty and sovereign rights. We call on Turkey to immediately end its illegal actions that undermine peace and security in the region,” the Foreign Ministry’s statement reads.

Greek Minister of State, Giorgos Gerapetritis, added the Oruc Reis was being monitored by the Greek navy.

“We are at full political and operational readiness,” Gerapetritis said on state television ERT.

“The majority of the fleet is ready at this moment to go out wherever is needed,” he added when asked to elaborate. “Our ships that are sailing in crucial areas were already in place days ago. If necessary, there will be a greater development of the fleet.”

Gerapetritis said that “it is clear that we are not seeking any tension in the region. On the other hand, our determination is a given.”

Greece on Monday issued its own maritime safety message saying the Turkish Navtex had been issued by an “unauthorised station” and referred to “unauthorised and illegal activity in an area that overlaps the Greek continental shelf.”

Turkey retorted with another maritime message saying the seismic survey was being conducted on Turkey’s continental shelf.

Speaking after a four-hour Cabinet meeting, Turkish President Recep Tayyip Erdogan warned that Turkey would not confine its offshore exploration efforts to its immediate coastline, but otherwise appeared conciliatory.

“Let’s come together as Mediterranean countries. Let’s find a formula that’s acceptable for everyone, that protects everyone’s rights,” he said in a televised speech.

He added: “We are always there and ready for the solution of disputes through dialogue and on a fair basis. We will continue to implement our own plans in the (eastern Mediterranean) and in the field of diplomacy until common sense prevails in this regard.”

At the crux of the dispute is whether islands should be included in calculating a country’s continental shelf and maritime zones of economic interest.

Turkey argues they should not be, a position Greece says violates international law. Greece has thousands of islands and islets in the Aegean and Ionian seas, around 200 of them inhabited.

READ MORE: ‘No need for discussion,’ says Erdogan as Turkey restarts drilling in eastern Mediterranean.

Greece is “formally” in the midst of a second wave of the coronavirus pandemic, one of the country’s top infectious disease experts has told The Guardian.

After recording its highest number of positive diagnoses ever, a record 203 cases on Sunday, the nation has reached a critical juncture in its ability to further contain the spread of the virus.

“We can say that Greece has formally entered a second wave of the epidemic. This is the point that we could win or lose the battle,” said Gkikas Magiorkinis, assistant professor of hygiene and epidemiology at Athens University.

The former Oxford University academic, among the expert scientists advising the government, forecasts cases climbing to 350 a day if the “dramatic increase” continued unabated.

“Unless there is a change in the trend that we are seeing, we are likely to propose more measures along the lines we have seen in Poros,” he added referring to the Argo Saronic island where a surge in cases late last week prompted authorities to announce an unprecedented crackdown including the closures of clubs, bars and restaurants from 11pm.

RELATED: Greek island on lockdown after worrying Covid-19 outbreak.

The Greek Health Minister, Vasillis Kikilias, announced late on Monday further containment measures, warning “transmission of the virus is growing dangerously.”

The measures mainly affect travelling from certain countries, operations hours in the catering sector in several regional units, as well as cultural and other events such a concerts.

Until this month, Greek health officials appeared to have the epidemic under control but Magiorkinis said the abrupt rise, compounded by a sudden jump in the number requiring intubation, up from nine on 1 August to 22 last night, left no doubt that the highly contagious disease was working its way through society.

Prior to additional precautionary measures being enforced last week, not least mask-wearing in all enclosed spaces, Greece had seen its effective reproductive number, or R number, reach 1.

“Our main concern is the degree to which this epidemic can stretch any health system,” he said.

“Greece currently has around 1,000 beds that can support COVID-19 patients … no health system, anywhere in the world, can cope effectively with a full epidemic resurgence. In the next two weeks we could have as many as 100 people intubated, almost matching the number we had at the height of the pandemic.”

Tourism has partly played a role for the sudden increase. But echoing government officials, Magiorkinis attributed the resurgence mostly to lax observance of hygiene protocols by Greeks, particularly younger generations who have flooded bars and beaches in recent weeks.