Russia has suspended talks with Turkey on a major gas pipeline project in the Black Sea, in a further escalation after Turkey downed a Russian warplane. The TurkStream project was designed to boost Russian gas exports to Turkey but now there are doubts about its future, as Russia tightens sanctions. Turkey is the second biggest customer of Russian gas after Germany. Russia began building part of TurkStream in May. The suspension of talks was announced by Russian Energy Minister Alexander Novak. Meanwhile, Turkey’s Prime Minister Ahmet Davutoglu has now said Ankara will speed up work on a pipeline called Tanap, to take delivery of Azerbaijani gas from the Caspian Sea.