Moscow (AFP) - Russian gas firm Gazprom said Sunday construction had begun of a gas pipeline under the Black Sea to Turkey meant to eventually also serve the European Union.

"Construction of the TurkStream gas pipeline began in the Black Sea near the Russian coast," Gazprom said in a statement.

"Implementation of the project is on schedule and our Turkish and European customers will from the end of 2019 have a reliable new route for importing Russian gas," said Gazprom's chief executive Alexei Miller in the statement.

Russia first floated the project in 2014 after the EU blocked plans for a pipeline under the Black Sea to Bulgaria at the height of the Ukraine crisis.

A diplomatic crisis following the shooting down of a Russian bomber overflying the Turkish-Syrian border delayed the project, which was revived when bilateral relations were mended last year.

Two lines capable of carrying 15.75 billion cubic metres of gas per year each will be built.

With Turkstream Russia aims to not only reinforce its capacity to deliver gas to Turkey, but to also make it a transit country in place of Ukraine, even if the prospects of that are uncertain given the EU's hostility towards new Russian pipelines.