Special OSCE representative in Ukraine Martin Sajdik has announced that a trilateral forum on the ongoing war in eastern Ukraine has "reached an agreement on a mutual release and exchange of conflict-related detainees by the end of the year."
It would be the second major prisoner exchange in four months in the five-year-old conflict between Ukrainian government forces and Russia-backed separatists in Ukraine's Donbas region.
Sajdik said in a statement on the OSCE website on December 23 that the breakthrough came during a video conference of the so-called Trilateral Contact Group -- comprising Russian, Ukrainian, and OSCE representatives -- with the participation of separatist groups that hold swaths of territory in Donetsk and Luhansk.
TASS had quoted Russia's envoy to the group, Boris Gryzlov, as saying earlier on December 23 that the deal had been done between Kyiv and the Donetsk and Luhansk groups, with Russian and OSCE mediation. But he provided no details.
Kyiv and the West accuse Russia of arming and aiding the separatists, but Moscow insists it is not a party to the conflict, which followed shortly after Russia occupied then annexed Crimea from Ukraine in March 2014.
On September 7, Russia and Ukraine exchanged a total of 70 prisoners in a move praised by the West as an opportunity to improve tense relations between Kyiv and Moscow. It was the first such exchange in two years.
Kremlin spokesman Dmitry Peskov then told reporters on October 4 that "certain work is being done in [the] direction" of a prisoner exchange with Ukraine.
Leaders of the so-called Normandy Four -- France, Germany, Ukraine, and Russia -- emerged from extensive peace talks in Paris on December 9 saying they had agreed to aim for an "an all-for-all" prisoner exchange by the end of the year.
Ukrainian President Volodymyr Zelenskiy said at the time that the prisoner swap would take place on December 24.
Russian President Vladimir Putin and Zelenskiy also reportedly agreed on December 9 to "commit to a full and comprehensive implementation" of a cease-fire in eastern Ukraine by the end of December.
The war in eastern Ukraine has killed more than 13,000 people since April 2014.