The incident in the Kerch Strait, gas transit via Ukraine after 2019, the situation in Syria and US’s plans to withdraw from the Intermediate-Range Nuclear Forces Treaty (INF Treaty) were in focus of telephone talks between German Chancellor Angela Merkel and Russian President Vladimir Putin, German government spokesman, Steffen Seibert, said on Monday.

"The chancellor and the president among other things discussed Russian gas transit via Ukraine after 2019, as well as the situation in Syria, especially the issue of the formation of the Constitutional Committee," he said. "Apart from that, they exchanged views on the situation around the INF Treaty."

"The conversation focused on the situation in the Kerch Strait," he noted. "The chancellor stressed that measures are needed to ensure free movement of ships."

Merkel, according to the spokesman, also called for the release of the detained Ukrainian sailors.