The head of Ukraine's Naftogaz has suggested the European Union could prevent Russia and Turkey from building the so-called Turkish Stream pipeline by blocking the use of deepwater building technology.

Andrey Kobolev, who heads the state-owned gas company, has told a Ukrainian TV station that EU could use sanctions to ban the transfer of such technology to either Russia or Turkey, countries that will need the help of Western companies to build the seabed section of the pipeline.

Turkish Stream, announced as a substitute to South Stream (which was to deliver Russian gas to Bulgaria, Serbia and further on to Central Europe) via the Black Sea, was called into question by a Russia-Turkey spat, but is back on the agenda as Ankara and Moscow are mending fences.

"It is a question of political will," Russian news agency RIA quotes him as saying.

He has also reiterated the project carries "certain risk" to Ukraine.

Moscow had been warning for months that gas transit via Ukraine's network would be halted once Turkish Stream is in place, but later took a more moderate stance.

Russia and Turkey are expected to confirm the political decision to build the pipeline at a meeting between their respective presidents, Vladimir Putin and Recep Tayyip Erdogan.