Ukrainian President Volodymyr Zelensky asked Pope Francis during a meeting in the Vatican for help in freeing Ukrainians held captive by Russia.

Zelensky, who is touring major European capitals to discuss his proposed "victory plan" for the war with Russia, said he had also invited the Vatican to attend a conference on prisoners of war to be held in Canada later this month.

"We are counting on the help of the Holy See for the release of Ukrainians held captive by Russia," Zelensky said in a social media post, adding that this was the main topic of his 35-minute conversation with the Pope.

The Vatican did not provide details of the pope's conversation with Zelensky, but said that in a subsequent meeting, the Ukrainian leader and the Vatican's top diplomat discussed "the war... as well as ways to end it."

This is the second meeting between Zelensky and Pope Francis in four months. They also met in June at the G7 summit in southern Italy.

On Friday, at the end of the meeting, the Pope presented Zelensky with a bronze work of art with a flower and a bird, with the inscription "Peace is a fragile flower".

Zelensky presented the Pope with an oil on canvas depicting a child among the ruins of the Ukrainian city of Bucha, which was occupied by Russian forces for 33 days in the spring of 2022.

Ukraine and the West accuse Russian forces of committing war crimes during the occupation of Bucha.

Zelensky is traveling to Europe this week to discuss his proposed "victory plan" with the leaders of Britain, France, Italy and Germany, as well as the head of NATO.

Western officials and Zelensky have said the war with Russia is at a critical point and Ukraine needs further support to try to change the balance on the battlefield and gain a strong position for eventual peace talks.

The pope drew the ire of Ukrainian officials in March when he suggested they should have the courage of a "white flag" and negotiate an end to the war with Russia.

At the time, Zelensky dismissed the Pope's statements as "virtual mediation" from a distance.

Francis also criticized plans by Ukrainian lawmakers to ban the activities of a Russian-linked branch of the Orthodox Church, which Ukrainians have accused of spreading pro-Russian propaganda and harboring spies.