Cyprus has initiated legal proceedings against three companies involved in gas drilling by Turkey to the west of the island for encroaching on the island's continental shelf, a senior foreign ministry official said on Tuesday.
Officials declined to name the companies, but said they were not Turkish.
Gas finds in the eastern Mediterranean in recent years have exposed tensions and claims of overlapping jurisdictions between the two countries, which do not have diplomatic relations.
A Turkish drill ship Fatih has been anchored west of Cyprus since last month, and another drill vessel Yavuz is scheduled to be deployed east of the island soon.
"We have already initiated legal proceedings against companies cooperating with the TPAO," the foreign ministry official said, referring to the state-owned Turkish petroleum company.
"We are determined to do the same with the Yavuz," the official said.
Both areas are claimed by the Cypriot government as its exclusive economic zone, where it has rights to explore for hydrocarbons. Turkey maintains an area west of Cyprus is its own continental shelf.
(Reporting by Michele Kambas, editing by Louise Heavens)