Russian President Vladimir Putin on Sunday congratulated Turkish leader Recep Tayyip Erdogan, who has collaborated closely with Russia on key international issues despite disagreements, on his re-election.

"Your victory in these elections is the logical result of your dedicated work as head of the Turkish Republic," Putin said, according to the Kremlin website.

Putin told Erdogan, who he called his "dear friend", that his victory was "clear evidence of the Turkish people's support for your efforts to strengthen state sovereignty and pursue an independent foreign policy".

The two leaders have not always seen eye-to-eye -- backing opposing players in conflicts in the Middle East and the ex-Soviet Caucasus region -- but they have developed strong ties over the years.

Most importantly, they see each other as reliable partners in challenging the West's economic, military and political dominance, observers told AFP.

Putin also told Erdogan that Russia "highly values your personal contribution to the development of friendly Russian-Turkish relations" and expressed "readiness to continue our constructive dialogue".

Turkey has leverage in key areas for Moscow, such as the war in Syria, the Kremlin's standoff with NATO, and the large-scale Ukraine offensive.

Ankara has delivered drones to Kyiv, but it has refused to join sanctions against Moscow, thus becoming an important alternative transit hub for heavily sanctioned Russian exports.

It has also mediated between Ukraine, the West and Russia, including by helping broker the deal that allowed Ukrainian grain exports to resume.

Putin praised the "great significance" of projects between Russia and Turkey, including the Russian-built Akkuyu nuclear power plant, Turkey's first.