Cyprus accused Turkey of escalating violations of the island nation's sovereign rights by sending a drillship to an area near its shores. The statement comes after the Turkish vessel Yavuz was spotted around 50 nautical miles (95 kilometres) south-west of the island earlier in the day.
The Cypriot government has already awarded exploration rights in the zone to Italian and French drillers, but Ankara claims it has the right to drill for regional natural resources.
Brussels, however, warned that the bloc might introduce measures in response to the Turkish activity in the region.
Cyprus has been divided since 1974 after Turkish troops arrived at the island claiming they had to protect local Turks from the Greek community. Nearly a decade later, the Turkish Republic of Northern Cyprus was declared, but currently, only Ankara recognises it.