A prisoner swap is under way between Russia and Ukraine, according to a statement from the president office’s of Ukraine.
The statement did not say who was being swapped, revealing only that the process was “ongoing”.
But a Ukrainian prosecutor earlier said those being freed include the filmmaker Oleg Sentsov and 24 Ukrainian sailors who were detained last year.
There has been no confirmation of the swaps from Russia.
Relatives of some of the detainees were reported to be gathering at airports in Kiev. Rumours that a prisoner swap was imminent spread in recent days after Sentsov was moved to Moscow from a prison in Russia’s Arctic north.
Who are the prisoners?
Sentsov was arrested during a protest against Russia’s annexation of Crimea in 2014 and found guilty of plotting terrorist acts.
He denied the charges and his trial was denounced by the US, EU and others as politically motivated.
The sailors detained were seized along with three naval ships as they attempted to pass through the Kerch Strait, the only access to Ukrainian ports on the Sea of Azov.
In May an international tribunal ordered Russia to release the sailors and vessels.
A Russian lawyer told the Tass news agency that several jailed Russian citizens were preparing for an exchange. According to the lawyer, they included Russians convicted of plotting attacks in Ukraine.
What’s the wider picture?
Ukraine’s new president, Volodymyr Zelensky, said when he took office earlier this year that ending the conflict with Russian-backed rebels in the east would be his top priority as president.
Fighting in the region has claimed about 13,000 lives since 2014, amid a failed ceasefire deal.
Mr Zelensky is a political novice who was a comedian before taking power. This wee, Ukraine’s parliament sat for the first time since the vote, with Mr Zelensky picking 35-year-old lawyer Oleksiy Honcharuk as his prime minister.
Prisoner swap with Russia under way, Ukraine says