Russia's Gazprom said on Monday it had completed the sea portion of the first line of the TurkStream offshore gas pipeline across the Black Sea.
Gazprom, which plans to complete the pipeline in 2019, said in a statement that 1,161 km, of pipe had been laid since it began construction last year.
The second line, designed to ship gas to south European countries such as Greece, Bulgaria and Italy, will be laid in the third quarter of 2018, the company said.
Russian Energy Minister Alexander Novak said this month that Turkey's approval for Gazprom's onshore portion of the TurkStream pipeline's second line was still pending.
Moscow, which relies on oil and gas revenue, sees new pipelines to Turkey and Germany - TurkStream and Nord Stream 2 - as crucial to increasing its market share in Europe.