Debaltseve Ukraine
Ukrainian President Petro Poroshenko addresses the media in Kiev Mykhailo Palinchak/Ukrainian Presidential Press Service/Reuters

Ukrainian President Petro Poroshenko says the freeing of soldiers who were held captive by rebels is under way, AP reports.

He stated on his Twitter account this evening that he has been informed by the Ukrainian national security that the process has begun.

"In the near future 140 of our heroes will be free," he tweeted.

He did not give details of when the release was taking place or how many captive rebels would be exchanged.

The recent ceasefire agreement included prisoner exchanges. While it appears that this part of the agreement is being adhered to – at least to some degree – the fighting still continues.

In December, the Washington Post revealed that Russia was holding 30 Ukranian soldiers in prisons within its own territory, but was refusing to treat them as prisoners-of-war.

In an article for the newspaper Mark Feygin, a Moscow lawyer, said that one of the Ukrainian prisoners – pilot Nadiya Savchenko – had been captured while in uniform. Video of her interrogation by separatists was uploaded to YouTube, before she was handed over to Russian intelligence services and transferred to Russia.

Prisoners-of-war have specific rights laid out as part of the Third Geneva Convention, which Feygin accused Putin's government of ignoring.

Despite claiming to have no involvement within the Ukraine conflict, Putin agreed to a ceasefire between the pro-Russian separatists in the Crimea and Ukraine's government – a deal brokered by Germany and France – on 12 February. However, the ceasefire broke down almost immediately.

Russia's aggressive stance regarding the Ukraine and the West's involvement in the country, has led to leading military and diplomatic experts to warn that the West has severely underestimated Putin's desire to create a resurgent Russian empire.