Umerov and Chiygoz – deputy chairmen of the Mejlis, the Crimean Tatar self-governing body that has been outlawed by Russian authorities – were unexpectedly released and flown to Turkey on October 25, RFE/RL reported.

Speaking to journalists on October 27 at Kyiv's Boryspil Airport upon arrival from Ankara, Umerov and Chiygoz said they would return to Crimea in the near future – despite being in the dark about the conditions of their release and not knowing whether Russia would permit them to travel there.

"I will go back home for sure," Umerov said. He said that two weeks before he and Chiygoz were released, two Russian Federal Security Service (FSB) officers in a hospital where he was being held urged him to write a letter to Russian President Vladimir Putin asking for clemency.

"I rejected their request and nobody told me anything about my possible release or conditions for my return to Crimea," Umerov said.

Chiygoz also said he had made no request for clemency or transfer and emphasized that he "will not hide" from the Russian authorities.

"If they arrest me again after I return to Crimea it will be their problem," he said.

Both men expressed their thanks to the European Union, the United States, the Parliamentary Assembly of the Council of Europe (PACE), international organizations, their lawyers, and the presidents of Turkey and Ukraine for their efforts to secure their release. They said they will continue to "fight" for the release of all Ukrainian citizens in Russian custody and the restoration of Kyiv's sovereignty over Crimea.

Mejlis Chairman Refat Chubarov read out the names of dozens of Ukrainian citizens who have been jailed by Russian authorities since Moscow occupied the region and seized control of the region in March 2014, sending in troops with unmarked uniforms and staging a referendum denounced as illegitimate by 100 countries including the United States and Ukraine.

Veteran Crimean Tatar leader Mustafa Dzhemilev, a member of the Ukrainian parliament, said that Turkish President Recep Tayyip Erdogan's efforts had made the release possible. Dzhemilev suggested that Putin agreed to release Chiygoz and Umerov because he was eager "to preserve close ties with Erdogan, as not so many world leaders shake hands with the Russian president these days."

Dzhemilev predicted that the Kremlin might use the release of the two Crimean Tatar leaders as leverage to seek the removal of sanctions imposed on Russia by the United States, the European Union, and others following its takeover of Crimea.

Read alsoCrimean Tatar leaders freed by Russia arrive in KyivRights groups say Russia has conducted a campaign of pressure and abuse against the Muslim Crimean Tatar minority and others who opposed the takeover.

At an appearance at the embassy in Ankara, Chiygoz said that he and Umerov did not know that they were headed for Turkey – and freedom – when they were on the plane.

"We were completely unaware what was going on. They took me from the detention center, Ilmi was taken from a hospital," said Chiygoz, suggesting they feared they were being sent to prison or some other fate in Russia.

"Known that the cruel repressions toward our people in Crimea are of a large scale, the only thing we could imagine then was an even worse development of events for us," he said.

Chiygoz was convicted of organizing an illegal demonstration and sentenced to eight years in prison on September 11 after what Amnesty International called a "sham trial."

Umerov was convicted of separatism on September 27 and sentenced to two years in a colony settlement, a penitentiary in which convicts usually live near a factory or farm where they are forced to work.

Umerov, who suffers from diabetes and Parkinson's disease, was confined to a psychiatric hospital in August 2016, a decision condemned by Human Rights Watch as "an egregious violation of his rights."

Read alsoUK's foreign minister for Europe welcomes release of Umerov and ChiygozRights groups and Western governments have condemned their convictions and calling them part of a pattern of oppression imposed by Russia since it seized Crimea.

In March, the European Parliament called on Russia to free more than 30 Ukrainian citizens it said were in prison or other conditions of restricted freedom in Russia, Crimea, and parts of eastern Ukraine that are controlled by Russia-backed separatists.

Most of them remain in custody. In a statement welcoming the release of Umerov and Chiygoz on October 25, the European Union demanded the immediate release of "all illegally detained Ukrainian citizens on the Crimean Peninsula and in Russia."

"The European Union expects Russia to reverse the decision to ban the activities of Mejlis, the self-governing body of the Crimean Tatars, and respect the rights of the Crimean Tatars, including those of freedom of assembly and expression," it said.