Turkish president did not identify the individual, but media speculated he was speaking about Ukrainian opposition figure Viktor Medvedchuk

Russian President Vladimir Putin asked Turkey to ensure the release of a particular person from Ukrainian custody, President Recep Tayyip Erdogan said, commenting on a Turkey-mediated prisoner exchange.

"One of the names was repeated many times by Mr. Putin. We have already sent this person to Russia," the Turkish president said, speaking to journalists on Friday.

Turkey served as an intermediary for an exchange of prisoners between Russia and Ukraine earlier this week. Some of the Ukrainian fighters released by Russia will stay in Turkey as what Erdogan described as his "guests." 

While the Turkish leader didn't identify the person sent to Russia, whose fate he claimed was of particular interest to Putin, some media outlets speculated that he was referring to Viktor Medvedchuk - a Ukrainian opposition politician who was arrested by the Ukrainian government for alleged treason. 

The Ukrainian politician was granted freedom by Kiev as part of the swap, according to officials in Kiev and the Russia-allied Donetsk People's Republic (DPR).

Ukrainian President Vladimir Zelensky claimed that his country got 200 fighters for the man, whom he branded a "fan of Russia." He also stated that five senior members of the Azov battalion, a unit in which some members espouse openly neo-Nazi ideology, will remain in Turkey.

DPR head Denis Pushilin credited Medvedchuk for negotiating multiple prisoner exchanges between DPR militia and Kiev in the past, explaining why the Ukrainian national was part of this week's swap.

Kremlin spokesman Dmitry Peskov on Friday declined to comment on Medvedchuk's whereabouts and urged journalists to check the official statement from the Defense Ministry on the prisoner swap, which didn't mention the politician.

Medvedchuk was the leader of an opposition party called 'Opposition Platform - For Life' (OPZZh), which had the second-largest faction in the Ukrainian parliament after Zelensky's political force, 'Servant of the People'. He advocated for reconciling with Russia, arguing that the escalating confrontation would be disastrous to his country.

The Ukrainian government arrested Medvedchuk last year on treason charges just after his party surpassed the president's in popularity. Kiev has since outlawed OPZZh, using the conflict with Russia as a justification for escalating the crackdown on politicians and media critical of Zelensky.