Cyprus has called Turkey's decision to send another oil and gas drilling ship into waters off its coast an "utterly provocative and aggressive" violation of its sovereign rights.
Ankara has employed "bullying tactics of an era long gone" by sending the most recent drill ship to a region off the island's southwestern coast, the presidency said in a strongly worded statement on Friday.
"This new provocation is exemplary of Turkey's defiance of the European Union's and the international community's repeated calls to cease its illegal activities," it said.
The ship, named the Yavuz, was about 94km (51 nautical miles) off the Cypriot coast on Friday.
The presidency said the region lies within the continental shelf of Cyprus and had been de-limited with Egypt "in accordance with international law". Nicosia has already licensed exploration rights in the area to Italian and French companies.
Cyprus urged Turkey to cease its "illegal activities and withdraw all its drilling and seismic vessels" from the region.
"It is yet another proof of the utterly provocative and aggressive behaviour of Ankara, which has chosen to speedily and irreversibly depart from international legality, thus putting security and stability in the Eastern Mediterranean at risk," the statement said.
Meanwhile, Cagatay Erciyes, head of the department of Turkey's foreign ministry looking into the eastern Mediterranean, announced on Twitter that the Yavuz will start a new round of drilling in the area on October 7.
Erciyes added the area was within Turkey's continental shelf and that Ankara has legal rights to drill there.
In July, the EU agreed to call off high-level political meetings, suspend negotiations on an aviation deal, and reduce EU accession funding earmarked for Ankara in response to the drilling.
The Turkish foreign ministry shrugged off those measures, saying the moves "will not affect in the slightest our country's determination to continue hydrocarbon activities in the Eastern Mediterranean".
Turkey has repeatedly claimed exploring rights off Cyprus, either through its own continental shelf or in zones where Turkish Cypriots have equal rights over any finds with Greek Cypriots.
The Mediterranean island nation has effectively been divided since 1974 when Turkish forces invaded northern Cyprus in response to an Athens-backed Greek Cypriot coup seeking union with Greece.
The country's internationally recognised government has since been seated in the Greek Cypriot south. A breakaway Turkish Cypriot state in the north is recognised only by Ankara, which keeps some 35,000 troops there.
In recent years, the discovery of huge gas reserves in the eastern Mediterranean has set off a race to tap underwater resources.