Pope Francis has called for peace and an end to the 'blind fury' of violence as he wrapped up a peace mission to South Sudan in east Africa.

Saying mass before a crowd of 70,000 people, the 86-year-old pope wove his homily around the themes that have dominated his trip to the world's newest nation, reconciliation and mutual forgiveness for past wrongs.

He asked people to make themselves immune to the "venom of hatred" to achieve the peace and prosperity that have eluded them through years of bloody ethnic conflicts.

"Let us lay down the weapons of hatred and revenge... Let us overcome the dislikes and aversions that over time have become chronic and risk pitting tribes and ethnic groups against one another," he said.

Afterwards, aboard a plane returning to Rome, the pope made further comments in support of the LGBT+ community. He also received full backing from two other Christian leaders with him, Archbishop of Canterbury Justin Welby and Moderator of the General Assembly of the Church of Scotland Iain Greenshields.

"The criminalisation of homosexuality is a problem that cannot be ignored," he said.

The Pope’s comments come after he declared last month that homosexuality was a sin, but not a crime.

A total of 66 United Nations member states continue to criminalise consensual same-sex sexual relations, according to data from ILGA World (the International Lesbian, Gay, Bisexual, Trans and Intersex Association). In several countries where same-sex relations are illegal, punishments can include a possible death penalty.

"This is not right," Pope Francis said.

"Persons with homosexual tendencies are children of God. God loves them. God accompanies them… condemning a person like this is a sin. Criminalising people with homosexual tendencies is an injustice".

He noted that the Catholic Church's catechism, or book of teachings, says same-sex attraction is not a sin but homosexual acts are. It also says that LGBT people should not be marginalised.

The pope mentioned his now-famous phase from soon after he became pope in 2013 that he could not judge people with same-sex tendencies who are seeking God.

He also noted that while visiting Ireland in 2018 he said that parents could not disown their LGBT children, but had to keep them in a loving family.

The pope repeated that the Catholic Church cannot permit sacramental marriage of same-sex couples but said that he supported so-called civil union legislation giving same-sex couples legal protection in issues such as pensions, inheritance and healthcare.

The "pilgrimage of peace" in South Sudan was the first time in Christian history that leaders of the Catholic, Anglican and Reformed traditions conducted a joint foreign visit.