Zelenskiy asks pope to help win release of prisoners of war

"(The pope) does everything possible to achieve peace and harmony throughout the world," Zelenskiy said in a Tweet afterwards.

"I asked for help with the release Ukrainians captured in Donbass, Crimea and Russia," he said.

Relations between Ukraine and Russia collapsed following Moscow's annexation of the Crimean peninsula in 2014 and its subsequent support for separatists in eastern Ukraine.

The Vatican has diplomatic relations with both Ukraine and Russia.