MOSCOW, April 10. /TASS/. Russian airline companies have received a telegram from the Federal Aviation Agency (Rosaviatsia) warning about a possible suspension of charter flights to Turkey, a source in one of the airlines told TASS.

"Rosaviatsia sent a telegram to Russian airlines stating that suspension of charter flights Russian airlines make to Turkey's airports is possible," he said.

A potential suspension of charter flights is related to a complicated political situation in Turkey, according to the source.

"According to the text of the telegram [sent by the federal aviation agency (Rosaviatsiya) to Russian air carriers - TASS], the potential suspension of charter flights to Turkey is related to the challenging political situation in Turkey," the source said.

It follows from the text of the telegram available with TASS that Rosaviatsiya asks airlines "to undertake required measures when planning existing charter programs." The telegram was signed by deputy head of the Russian aviation agency Oleg Kim.

Previously Russia suspended charter flights with Turkey in late October 2015. That was done after the Turkish Air Forces had attacked a Russian bomber which was on a mission in the sky over Syria as part of an anti-terrorist operation.

In August 2016, after the President of Turkey apologized for the incident and negotiations between the two leaders, the parties decided to start the restoration of ties. Russian experts from the Transport Ministry studied inspected the safety of Turkish airports and the sent a corresponding report to the government.

On August 28, 2016, Prime Minister Dmitry Medvedev signed a decree on lifting the ban on charter air services between Russia and Turkey.