A Turkish navy corvette was spotted sailing in Greek waters in the early hours of Tuesday, the Defense Ministry said, adding that the vessel was closely monitored until it re-entered Turkish territory.

The TCG Buyukada sailed from the Gulf of Saros in northwestern Turkey, heading in a southwesterly direction. It was seen passing the Greek islands of Kea and Kythnos, the latter being just over 100 kilometers from the port of Piraeus.

"No Turkish vessel will be permitted to wander around without being watched," newly appointed Defense Minister Nikos Dendias told Antenna TV on Tuesday.