Opposition activist Leonid Razvozzhayev's defense team possesses information proving that he was seized in Ukraine in a special operation conducted by Russian law enforcement agencies, lawyer Violetta Volkova said.

"We have managed to find out that, according to Ukrainian law enforcement agencies, the said special operation was conducted by Russian forces on Ukrainian territory, and we will post an audio record of this conversation on the Internet today," Volkova said at a press conference in Moscow on Tuesday.

Hence, Russian law enforcement bodies detained Razvozzhayev on Ukrainian territory and then brought him to Moscow, she said.

"This grossly violates international law and the extradition laws. Leonid was not declared internationally wanted, and therefore no special operations could have been conducted involving him," she said.

The news about Razvozzhayev's voluntary surrender and confession appeared two days after it was reported that he had gone missing in Ukraine, she said.

"Two days passed from Friday to Sunday, when Leonid turned up at a court hearing dealing with his arrest. In this period, his whereabouts were unknown, and it is unclear where he was and what influence he had been subjected to," she said.

Razvozzhayev, whom Russian law enforcement agencies accused, along with some other opposition members, of preparing disturbances based on allegations made in the documentary film Anatomy of Protest-2, disappeared from Kyiv on October 21. The next day, the Russian Investigative Committee announced that he had filed for voluntary surrender in Moscow.

However, Razvozzhayev, whose arrest was sanctioned by a Moscow court, managed to tell journalists near the courthouse while being escorted to prison that he had been tortured for two days.

Razvozzhayev's associates and numerous human rights activists doubted the investigation's claim that he had surrendered voluntarily.