The Vatican acknowledged in a statement from its culture and human development departments that papal documents from the 15th century were used by colonial powers to give legitimacy to their actions, which included slavery.

The departments specifically mentioned the papal bulls Dum Diversas (Until Different) from 1452, Romanus Pontifex (The Roman Pontiff) from 1455, and Inter Caetera (Among Other Things) from 1493.

"Historical research clearly demonstrates that the papal documents in question, written in a specific historical period and linked to political questions, have never been considered expressions of the Catholic faith," the departments said.

They said they "were manipulated for political purposes by competing colonial powers in order to justify immoral acts against indigenous peoples that were carried out, at times, without opposition from ecclesiastical authorities".

The Vatican departments admitted that the bulls, which gave political cover to Spanish and Portuguese conquests in Africa and the Americas, "did not adequately reflect the equal dignity and rights of indigenous peoples".

"It is only just to recognise these errors, acknowledge the terrible effects of the assimilation policies and the pain experienced by indigenous peoples, and ask for pardon," they said.

The Roman Catholic Church has long faced accusations of being complicit with colonial abuses committed by Western invaders and their descendants claiming to be spreading the Christian faith.

Argentine-born Pope Francis, the first pontiff from the Americas, has made several outreach gestures towards indigenous people. Last year, he travelled to Canada's Arctic region to apologise for the oppression of the Inuit people.

In 2007, Francis' predecessor, Benedict XVI, published a book that condemned rich countries for having mercilessly "plundered and sacked" Africa and other poor regions, and for exporting to them the "cynicism of a world without God".

(Reporting by Alvise Armellini, editing by)