Pope Francis will travel to Canada at the end of July, where he is expected to meet Indigenous survivors of abuse committed at church-run residential schools, the Vatican said on Friday.

The 85-year-old, who will travel to the cities of Edmonton, Quebec and Iqaluit, apologised last month to Indigenous delegations who visited him at the Vatican over a scandal that has rocked the Catholic Church.

Numerous investigations into the former residential schools are under way after the discovery of mass unmarked graves, with more than 4,000 children believed to be missing.

Further details on the July 24-30 visit will be published in the coming weeks, the Vatican said.

Canadian Prime Minister Justin Trudeau said on Friday that "a formal in-person apology" from the head of the Roman Catholic Church to survivors and their families would be an important step "to advance meaningful reconciliation for Indigenous Peoples in our country".

Francis had earlier said he was keen to visit Canada, but the trip was far from certain due to a painful knee problem that has forced him to begin using a wheelchair.

A visit to Lebanon initially planned for June was postponed earlier this month over health concerns.

The Argentine pontiff confirmed on Friday however that he would be travelling to South Sudan "in a few weeks' time", along with the Church of England's most senior cleric, Archbishop Justin Welby. (AFP)