"There is intense diplomacy going on behind the scenes, with European states leading this endeavour, and we are expecting today to see results of these efforts," government spokesman Nicos Christoulides told state radio.

"Very specific actions are being taken but cannot be made public in order not to affect these efforts. However, efforts are being made at various levels, not just diplomatic ones. I think the next 24 hours will be decisive," he said.

Christoulides said the government had also received reassuring calls from other energy companies with a license to exploit riches in Cyprus's exclusive economic zone.

"They expressed their confidence in the Cypriot EEZ and will proceed normally and will not be affected in any way by what is happening at the moment," he said.

"What is most important at this moment is the drillship reaches its destination and begins drilling," said Christoulides, who is take over as foreign minister of the EU member state on March 1.

Turkish President Recep Tayyip Erdogan has warned foreign energy companies not to "overstep the mark" in the Mediterranean after Turkey's warships blocked the Italian drilling vessel.

On Monday, EU President Donald Tusk urged Turkey on Twitter to "avoid threats or actions against any EU member".

Turkey should "instead commit to good neighbourly relations, peaceful dispute settlement and respect for territorial sovereignty", he said.

Italy's Defence Minister Roberta Pinotti, quoted by Italian news agency AGI on arrival Wednesday in Brussels for a NATO summit, said Rome had "opened all diplomatic channels with Turkey to reach a shared solution that we hope will be rapid".

The standoff over exploiting energy resources in the eastern Mediterranean risks further complicating stalled efforts to reunify Cyprus following the collapse of UN-brokered peace talks last year.

Italy's energy giant ENI said its ship had been ordered to stop by Turkish ships last week over "military activities in the destination area" as it was on course to start exploring in block 3 of Cyprus's exclusive economic zone.

Cyprus has been divided since 1974 when Turkish troops invaded and occupied the northern third of the island in response to a Greek military junta-sponsored coup.

While the Greek-majority Republic of Cyprus is internationally recognised, the breakaway Turkish Republic of Northern Cyprus is recognised only by Ankara.

Turkey and Cyprus have long argued over the eastern Mediterranean, and Ankara has been stringent in defending the claims of Turkish Cypriots for a share of energy resources.

Cyprus expects more exploratory drills, with US giant ExxonMobil also planning two drills in the second half of 2018.

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EXXONMOBIL

ENI