The Turkish President assured his Ukrainian counterpart that he would not recognize Crimea's annexation by Russia, said the Ukrainian presidency in an official statement on Sunday.

The statement said Recep Tayyip Erdogan phoned Petro Poroshenko and assured him that despite Turkey and Russia's improving relations, he would not recognize the annexation.

"Erdogan confirmed that Turkey's support for Ukraine's territorial integrity is invariable," it said, insisting that Ankara would also unfailingly continue to back the Tatars in Crimea.

Since Russia's annexation of the peninsula, Erdogan, who backed Ukraine in the conflict, had frequently denounced the persecution of the Tatar minority by local authorities.

Russia's president Vladimir Putin arrived in Crimea on Friday, days after he accused Ukrainian military troops of attempting to infiltrate Crimean territory.

The United Nations Human Rights Commission estimated that nearly 10,000 people have been killed in the conflict area in eastern Ukraine since 2014.