Pope Francis and Muslim, Jewish, Hindu, Buddhist and Christian leaders pledged on Tuesday to use their religions to help stamp out modern slavery and human trafficking by 2020.
Francis was lead signatory of a declaration also signed by among others the head of the Anglican Communion, two rabbis, a Hindu from India, a Vietnamese Buddhist, an Egyptian imam and an Iraqi ayatollah. It called human trafficking, forced labor and prostitution and organ trafficking "a crime against humanity".
"The physical, economic, sexual and psychological exploitation of men and women, boys and girls, is chaining tens of millions of persons to inhumanity and humiliation," the pope said, before signing the pledge to do "all in our power, within our faith communities and beyond" to end modern slavery.
The leader of the world's 1.2 billion Roman Catholics called modern slavery "an atrocious plague."
The second global slavery index released last month by the Walk Free Foundation, an Australia-based human rights group, estimated that almost 36 million people were living as slaves, trafficked into brothels, forced into manual labor, victims of debt bondage or born into servitude.
Patriarch Bartholomew, spiritual head of the world's 300 million Orthodox Christians, addressed the group via a video link-up from his base in Istanbul.
The event was organised by the Global Freedom Network, a multi-faith, anti-slavery group.
Organizers said religious leaders could inspire their faithful to combat slavery and human trafficking through education, funding, demanding legal reform and enforcement and promoting ethical purchasing to avoid buying goods that could be the product of forced labor.