Pope Francis met Palestinian President Mahmoud Abbas at the Vatican on Thursday, their first face-to-face encounter in three years, as the pontiff has become more vocal in his criticism of Israel's military campaign in Gaza.

The two men held private talks for a half-hour, the Vatican said but offered few other details about the meeting.

A statement said Abbas also met afterwards with the Catholic Church's top diplomatic officials to discuss the "very serious humanitarian situation in Gaza, where it is hoped that there will be a ceasefire and the release of all hostages as soon as possible".

Abbas said in a statement that he thanked the pope "for his positions in support of achieving a just peace in Palestine based on the two-state solution".

Abbas is in Rome for a brief visit this week. He is also due to meet Italian President Sergio Mattarella and Prime Minister Giorgia Meloni on Friday.

The pope, as leader of the 1.4-billion-member Roman Catholic Church, is usually careful about taking sides in conflicts, but has recently been more outspoken about Israel's campaign in its ongoing conflict with the militant group Hamas.

In November, Francis suggested the global community should study whether Israel's campaign in Gaza constitutes a genocide of the Palestinian people. The comment, in a forthcoming book, drew a public rebuke from Israel's ambassador to the Holy See.

Israel says accusations of genocide in Gaza are baseless and that it is solely hunting down Hamas and other armed groups.

Gaza authorities say almost 45,000 Palestinians have been killed and more than 106,000 injured in Israel's offensive, while most of Gaza's 2 million people are homeless or displaced as famine looms.

Abbas and Francis last met in person in November 2021. During their visit together on Thursday, Francis gifted the president a bronze artwork inscribed with the words "Peace is a fragile flower," a gift the pope has also given other world leaders.

Abbas' trip to Rome comes as Lebanese Prime Minister Najib Mikati is also due to make a visit to Italy. Mikati is scheduled to meet Francis on Friday.

The pope has also criticised Israel's airstrikes in Lebanon, where it is fighting the Hezbollah militant group, as going "beyond morality".