Pope Leo has visited Istanbul's Blue Mosque, removing his shoes in a sign of respect but not appearing to pray in his first visit as leader of the Catholic Church to a Muslim place of worship during his four-day visit to Turkey.

Despite the Vatican earlier saying he would observe a 'brief moment of silent prayer', when invited to do so by the imam because it was 'Allah's house', the Pope declined.

Later, Vatican spokesman Matteo Bruni said: "The Pope experienced his visit to the mosque in silence, in a spirit of contemplation and listening, with deep respect for the place and the faith of those who gather there in prayer."

The Vatican then sent out a corrected version of its earlier bulletin about the trip, removing a reference to the planned moment of prayer, without further explanation.

During his visit,the Pope bowed slightly before entering the 17th century mosque and was led on a tour of the expansive complex, able to hold 10,000 worshippers, by its imam and the mufti of Istanbul.

Leo, walking in white socks, smiled during the 20-minute visit and joked with one of his guides, the mosque's lead muezzin - the official who leads the daily calls to prayer.

The Blue Mosque is officially named for Sultan Ahmed I, leader of the Ottoman Empire from 1603 to 1617, who oversaw its construction. It is decorated with thousands of blue ceramic tiles, the basis of its popular name.

(Some reporting by Reuters)