Pope Francis on Saturday paused for two minutes and clasped his hands in reflection during a visit to the Sultan Ahmet mosque in Istanbul, an AFP correspondent reported.
The pope closed his eyes, clasped his hands in front of his chest beneath the cross he wears around his neck and bowed his head, as he stood next to Istanbul Mufti Rahmi Yaran who performed an Islamic prayer known as the dua.
Francis' gesture was remarkably similar to that of his predecessor Benedict XVI who visited the mosque on the last papal visit to Turkey in 2006.
Benedict assumed the Muslim attitude of prayer and turned towards Mecca in what many saw as a stunning gesture of reconciliation between Islam and Christianity.
The Vatican later made clear he had not actually prayed in the mosque but was "in meditation" and had indicated that Pope Francis would make a similar gesture in this visit.
Francis then left the Sultan Ahmet mosque -- known abroad as the Blue Mosque and one of the great masterpieces of Ottoman architecture -- and headed to his visit of the Hagia Sophia museum.