Ukraine and Russia have agreed to a prisoner swap expected to involve a total of 277 people taken captive during the eastern Ukraine conflict, a senior Ukrainian official said Thursday. 

Roman Bezsmertny, a Ukrainian politician, said Kiev expected to exchange 208 people serving jail sentences in Ukraine for 69 Ukrainians. 

"The most important - an agreement was reached on the start of exchange procedure of prisoners of war, illegally held, convicted persons in the ratio of 208 to 69," he said.

Bezsmertny represents Ukraine in the working group on political issues of the Trilateral Contact Group, a body that aims to facilitate a diplomatic resolution to the conflict. 

The accord was concluded in the Belarus capital of Minsk following talks in the trilateral group, whose other members are Russia and the Organization for Security and Co-operation in Europe, a European security body tasked with monitoring a 2015 ceasefire agreement. 

Bezsmertny gave no exact date for the exchange but said the preparatory procedures could take up to several months.

Vadym Prystaiko, a senior presidential official and the nominee for the post of Ukrainian foreign minister, this week said Ukraine and Russia agreed that this exchange could take place over the next month. 

Kiev's forces have been battling pro-Russian separatists in the Donbass region of eastern Ukraine since 2014, in a conflict that has claimed more than 13,000 lives. Sporadic fighting continues despite the ceasefire agreement. 

In the last prisoner exchange in December 2017, Ukraine handed over approximately 300 captives to pro-Russian separatists and took back around 70, but disagreements have prevented any further swaps since then. 

Russia still holds dozens of Ukrainian captives from the conflict but it is unclear how many Russians are being held in Ukraine.