A key round of negotiations aimed at ending the fighting in eastern Ukraine has been unexpectedly called off.
Belarusian officials, who were set to host the continuation of talks in their capital, Minsk, starting today, had no immediate comment on the reason for the cancellation.
"The latest talks also included Russia and the Organization for Security and Co-operation in Europe (OSCE).
"Friday's round had been expected to tackle issues including the withdrawal of heavy weapons from the front line, the exchange of prisoners and ending Ukraine's economic blockade of rebel-held areas."
The meeting in Minsk was meant to iron-out the removal of heavy weapons from the battlefield and otherwise to improve a cease-fire deal agreed in September but frequently breached in the intervening weeks.
Euro news reports that the breakdown could be the result of a failure of Russian-backed militants to fulfill a prisoner swap agreed to on Wednesday.
Reuters says of the exchange: "The agreement to swap 125 Ukrainian servicemen for 225 rebels held by Kiev followed peace talks between envoys of Ukraine, Russia, the separatists and European security watchdog OSCE on Wednesday."
Denis Pushilin, a representative of the self-declared breakaway Donetsk People's Republic, was quoted by Russia Today as declining to comment on the negotiations while they are still in progress, although he acknowledged that "The date of the next round of talks remains uncertain."