Pope Benedict XVI is set to become the first head of the Roman Catholic Church to enter a mosque in Jerusalem when he visits the Holy Land in May, according to Vatican diplomats.

Monsignor Antonio Franco, the papal nuncio in Israel, said it had been agreed "in principle" that the pontiff would visit the seventh century Dome of the Rock, one of the holiest sites in Islam, together with the Grand Mufti of Jerusalem. It contains a rock on which the Prophet Muhammed is said to have left his footprint as he ascended to heaven on a "night journey" accompanied by the archangel Gabriel.

According to Koranic tradition, Muhammed and Gabriel rode from Mecca on a winged horse named El Buraq (meaning `lightning'), stopping briefly at Mount Sinai and Bethlehem before finally alighting at Temple Mount in Jerusalem, where they encountered Jesus, Abraham and Moses. Gabriel then took Muhammed to the pinnacle of the rock, where a ladder of golden light materialised on which Muhammed ascended "into the presence of Allah" before returning to Mecca.

Asked about reports that Pope Benedict may visit the nearby al-Aqsa Mosque, which is also on Temple Mount (known to Muslims as Haram al Sharif, or the Noble Sanctuary) and is also identified with Muhammad's "night journey", Monsignor Franco said this ''had not been spoken about''. In 2000 Pope John Paul II visited Temple Mount, but did not enter either of the mosques.

The Pope confirmed last Sunday that he will be travelling to the Holy Land from 8-15 May, taking in Jordan, Jerusalem, Nazareth and Bethlehem. In Jerusalem the Pope will visit the Yad Vashem Holocaust memorial but will not enter the adjoining museum because it contains an exhibit condemning Pope Pius XII, the wartime pontiff (1939-58) for his failure to speak out against the Nazi extermination of the Jews.

Monsignor Franco said Pope Benedict would also visit the Western Wall in Jerusalem, one of the holiest sites in Judaism, where John Paul II prayed in 2000. He said the papal trip was "a religious pilgrimage, not a political mission", adding: "The intent of the Holy Father's visit is to express his solidarity and closeness to the people of Israel and Palestine, and through them to all the people of this region".

Pope Benedict stood in silent prayer at the Blue Mosque in Istanbul in November 2006 in an attempt to mend relations with the Muslim world after an outcry over his controversial comments in Regensburg in his native Germany, in which he appeared to suggest that Islam was inherently violent and irrational.