In a gesture meant to unite the Christian community and "purify our wounded memories," the Vatican returned relics taken in 1204 to their rightful owners on Saturday.

The bones of two Orthodox Christian saints – Patriarchs John Chrysostom and Gregory Nazianzen, – were handed over to the spiritual leader of the world's Orthodox Christians, Ecumenical Patriarch Bartholomew I.

The bones were stolen from Constantinople by the Crusaders, say the Orthodox, while the Vatican maintains Byzantine monks brought them to Rome in the 8th century.

Before the saints' remains – kept in crystal and alabaster reliquaries – returned to Istanbul, they were blessed by both religious leaders in a colourful ceremony at St. Peter's Basilica.

A frail Pope John Paul II told those in attendance that this is an occasion to "purify our wounded memories" and to "strengthen our path of reconciliation."

Bartholomew remarked that the relics' return repairs "an anomaly" and "ecclesiastical injustice" but also proves there's no problem that can not be overcome by the Church of Christ.

The Vatican is retaining a small part of the relics.

In 2001, the pope apologized for Roman Catholic involvement in the Constantinople siege.

Back in Istanbul, the city's Greek community and dozens of clerics were on hand to witness the arrival of the relics as they entered the courtyard of the Cathedral of St. George, Bartholomew's church.

This is not the first time the Vatican has returned religious reliquary to its original owner.

In August, an icon returned to Russia prompted the country's Orthodox Church to accuse the Vatican of poaching for converts on its territory, a charge the Vatican denies.