Pope Leo is among world leaders invited to join U.S. President Donald Trump's "Board of Peace", Cardinal Pietro Parolin, the Vatican's top diplomatic official, said on Wednesday.

Leo, the first U.S. pope and a critic of some of Trump's policies, is evaluating the invitation, he said.

"The pope has received an invitation and we are considering what to do," Parolin told journalists. "I believe it will be something that requires a bit of time for consideration before giving a response."

The board was initially aimed at ending the conflict in Gaza, however Trump has said it will have a much broader remit and resolve conflicts globally.

While some countries, such as Israel and Egypt, have accepted the invitation, a number of others have expressed caution with diplomats warning it could harm the work of the United Nations.

The Vatican press office did not immediately respond to a request for comment about Parolin's remarks.

Leo, who has shown a robust but quiet diplomatic style since being elected pope last May, has decried conditions for Palestinians living in Gaza several times, including in a forceful sermon on Christmas Eve.

The pope, leader of the world's 1.4 billion Catholics, rarely joins international boards. The Vatican has an extensive diplomatic service and is a permanent observer at the United Nations, often taking part in debates.