Ukraine's main security agency says it welcomes "any steps" by Russia that would facilitate exchanges of people held by Kyiv and the Russia-backed separatists in eastern Ukraine.
The Ukrainian Security Service (SBU) made the remark in a brief statement on November 16, a day after Russian President Vladimir Putin told separatist leaders in Ukraine's Luhansk and Donetsk regions that he favored a plan for a prisoner swap with Kyiv.
The SBU "welcomes any steps taken by the Russian authorities to unblock the release of hostages," it said.
Russian state-run news agency TASS on November 15 quoted Kremlin spokesman Dmitry Peskov as saying Putin spoke by phone with separatist leaders Aleksandr Zakharchenko of the Donetsk region and Igor Plotnitsky of Luhansk.
The conversations came after Putin promised Viktor Medvedchuk, leader of the pro-Russian Ukrainian organization Choice, that he would speak to the separatists about a prisoner exchange with the authorities in Kyiv.
"Putin told them that he had supported Medvedchuk's proposal on large-scale exchanges of people held by both sides," Peskov said.
Peskov said that Zakharchenko and Plotnitsky supported a swap in principle but "pointed out that the issue will have to be worked out further on with representatives of Ukraine."
The Russian statements saying that Putin spoke directly to the Russia-backed separatist leaders represented a rare public acknowledgment of such direct contacts.
The separatists have controlled the capitals and some other districts of the Luhansk and Donetsk regions since the spring of 2014, when Moscow fomented separatism amid unrest that led to the downfall of Moscow-friendly Ukrainian President Viktor Yanukovych that February.
Russia does not recognize the separatist-held areas as independent and says it supports Ukraine's territorial integrity. Moscow also denies providing the separatists with troops, weapons, and other support in a war that has killed 10,000 people in the two regions since April 2014, despite what Kyiv and NATO say is incontrovertible evidence of such support.
In the past, the only official platform for Putin to meet the separatist leaders was during negotiations in the Belarusian capital in September 2014 and February 2015, when successive agreements known as the Minsk protocols were signed.
The agreements eased fighting but failed to stop it, and progress on other aspects of the 2015 deal -- which called for the "release and exchange of all hostages and illegally held persons" -- has been limited.
Medvedchuk, who has personal ties to Putin and has played a key role in previous prisoner swaps, told Putin that Ukrainian authorities had said they are ready to release 306 prisoners captured during the conflict in exchange for 76 Ukrainians held by the separatists.
Iryna Herashchenko, first deputy speaker of parliament in Ukraine, said that there had been no releases for 14 months and that Kyiv had long been ready "to hand over all of those who can be released under Ukrainian laws in order to take confirmed Ukrainians in exchange."
But she said that Ukraine would not bend to "blackmail" and suggested that Russia and the separatists were trying to get Ukraine to hand over former security-force officers accused of involvement in deadly crackdowns on demonstrators during the Euromaidan protests in Kyiv that pushed Yanukovych from power.
In a post on Facebook on November 15, Herashchenko said that Ukraine "cannot release those who...cannot be released in accordance with the Minsk agreements."
Medvedchuk said the pace of exchanges has been slow because of the "all-for-all" formula established by the sides and enshrined in the 2015 Minsk agreement.