Pope John Paul II (search), in a gesture of friendship with the Orthodox Church, on Saturday handed over the bones of two early Christian saints that were brought to Rome from ancient Constantinople centuries ago.

The Vatican said the return of the saints' relics was part of the pope's efforts to promote Christian unity and dismissed any suggestion that John Paul was "asking pardon" for their removal by Crusaders from the seat of the Orthodox Church (search).

The pope sat beside Ecumenical Patriarch Bartholomew I (search), spiritual leader of the world's Orthodox Christians, in St. Peter's Basilica as the bones of the saints, resting on yellow velvet in crystal and alabaster reliquaries, were brought to the altar.

While a choir sang in Greek and Latin, the two religious leaders blessed the relics, before the reliquaries were carried away on biers by Vatican ushers in dark suits acting as pallbearers.

The Vatican is retaining a small part of the relics.

During a visit to the Vatican in June, the Orthodox leader had sought the return of the relics of Patriarchs John Chrysostom (search) and Gregory Nazianzen (search), who were archbishops long before the split between the eastern and western churches nearly 1,000 years ago.

In remarks read for him by an aide, the frail pontiff called it a "blessed occasion to purify our wounded memories" and to "strengthen our path of reconciliation."

"I will never tire" in efforts to achieve it, the pope said.

Bartholomew, speaking next, said the handover repaired "an anomaly" and "ecclesiastical injustice" and that it was a sign that there are no "insurmountable problems in the Church of Christ."

The Orthodox leader, speaking in Italian, said the gesture also served as an example to those holding religious treasures sought by others.

In Istanbul later Saturday, bells rang out in celebration as the remains were carried in a candle light procession into the Cathedral of St. George.

"For eight hundred years, these relics have been in exile," Bartholomew said at service. "This gesture differentiates (Catholic leaders) from the deed of their predecessors eight centuries ago."

Clear glass cases containing the bones were symbolically placed in front of patriarch's throne. Bartholomew bowed and crossed himself as hymns of praise were chanted.

Bartholomew and John Paul have both emphasized reconciliation between their churches, which split in 1054 over the growing power of the papacy.

The Orthodox say the relics were removed from Constantinople when Crusaders sacked the city in 1204.

The Vatican, however, says the bones of one of the saints, Gregory, were brought to Rome by Byzantine monks in the 8th century.

In a statement issued Saturday, papal spokesman Joaquin Navarro-Valls emphasized that Gregory's remains were brought to Rome in the earlier century and denied that the pope was seeking pardon for the removal of the saints' remains.

"Without negating the tragic events of the XIII century," Navarro-Valls said, the gesture was intended to promote unity between Catholics and Orthodox.

The remains have been kept in St. Peter's Basilica.

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

The pope has made reconciliation among the divided Christian churches one of the major themes of his papacy, but progress has been limited.

In August, he sent to Moscow an icon dear to Russian Orthodox believers.

John Paul has also apologized for sins committed by Catholics against other Christians.

In recent years, however, new strains have arisen.

The Russian Orthodox Church has accused the Vatican of poaching for converts in traditional Orthodox territory, a charge the Vatican firmly denies.

The Greek Orthodox Byzantine Empire ultimately collapsed when the Muslim Ottoman Turks conquered the city in 1453, but the Ecumenical Patriarchate remained in the city.

Bartholomew is considered "first among equals" among Orthodox patriarchs and directly controls several Greek Orthodox churches around the world.