Pope Benedict joined Muslims and Jews in singing a peace song during a trip to Nazareth.
At the end of a meeting involving representatives from different faiths, a rabbi announced he had composed a song using Arabic, Hebrew and English phrases about peace.
A Vatican spokesman said the Pope did not expect to be invited to sing the song but he joined in while the audience held hands and swayed along with the music.
Rabbi David Rosen of the American Jewish Committee was on the stage with the Pope. He said: "It illustrated dramatically that religion does not have to be the problem but the solution and that it is up to politicians to engage religious leaders in the search for peace."