Istanbul (AFP) - Pope Francis on Sunday was attending a divine liturgy led by Orthodox Ecumenical Patriarch Bartholomew I, wrapping up his first visit to Turkey where he has sought to reach out both to Muslims and other Christian confessions.Francis's attendance at the divine liturgy at the Patriarchal Church of St. George on the banks of the Golden Horn in Istanbul was the latest sign of the warming ties between the Roman Catholic and Orthodox Churches under his papacy.The visit of the pope to Istanbul -- once the capital of the Christian Byzantine world and formerly known as Constantinople -- has been heavily loaded with symbolism.On Saturday, the pope during a visit to the Sultan Ahmet mosque -- better known abroad as the Blue Mosque -- turned towards Mecca and stood in two minutes of reflection next to a top Islamic cleric.Later in the day, he bowed his head and asked Bartholomew to kiss him on his brow, in a remarkable sign of humility towards Bartholomew, the "first among equals" of the Orthodox Church.The pope and Bartholomew have in the last months worked hard for a rapprochement between the eastern and western churches which have been split since the schism of 1054.Their meeting is the latest positive step in a reconciliation process that began in 1964 with the famous embrace between Pope Paul VI and Ecumenical Patriarch Athenagoras, the first such meeting since the 15th century.The pope is due to sign a common declaration with Bartholomew -- whose official title is Archbishop of Constantinople, New Rome and Ecumenical Patriarch -- before returning to Rome in the afternoon.Bartholomew, who commands considerable respect beyond the Orthodox Church, holds an office that dates back to the early days of the Byzantine Empire, over a millennium before the Ottoman conquest of Constantinople in 1453.The patriarchate in Istanbul remains his "headquarters", and the patriarch himself must under Turkish law be a citizen of the country. - 'A beautiful moment' - Turkey's own Christian community is tiny -- just 80,000 in a country of some 75 million Muslims -- but also extremely mixed, consisting of Armenians, Greek Orthodox, Franco-Levantines, Syriac Orthodox and Chaldeans.Of these only the small Franco-Levantine and Chaldean communities regard the pope as the head of their churches.The trip has been marked by crowds far thinner than on Francis's previous visits abroad but also the heaviest security, which extended to positioning snipers on the balconies of mosque minarets.The pope has at times looked fatigued during a crammed three day programme in Ankara and Istanbul but was often seen breaking into a smile at the sight of an old acquaintance. The visit has been seen as a chance to build bridges between faiths amid the rampage by Islamic State (IS) jihadists in Iraq and Syria and concerns over the persecution of Christian minorities in the Middle East.After talks with Turkish President Recep Tayyip Erdogan in Ankara on Friday, the pope called for dialogue between faiths to end the Islamist extremism.However Erdogan had appeared to highlight the differences between the Muslim and Christian worlds, sounding the alarm against "rising Islamophobia".A Vatican official described Francis's gesture in the Blue Mosque as a "silent adoration", using a term for religious reverence, making clear he did not perform a prayer."It was a beautiful moment of inter-religious dialogue," added Vatican spokesman Federico Lombardi.The pope clasped his hands in front of his chest while Istanbul Mufti Rahmi Yaran performed an Islamic prayer with his hands in front and palms facing up.The trip has been less controversial than the last by a pontiff to mainly Muslim Turkey -- the visit by Pope Francis' predecessor Benedict XVI in 2006 which was overshadowed by remarks he had previously made deemed to be anti-Islamic.Lombardi described the atmosphere this time as more "cordial and serene" than during Benedict's visit.Papal visits to Turkey are still a rarity -- Francis will be just the fourth pope to visit the country after Benedict in 2006, John Paul II in 1979 and Paul VI in 1967.Join the conversation about this story »