VATICAN CITY — Religious leaders from a half-dozen faiths signed a new Vatican initiative Tuesday to end modern-day slavery by 2020, declaring that human trafficking, organ trafficking and forced labor and prostitution are crimes against humanity.

Pope Francis was joined by the Hindu guru Mata Amritanandamayi, known as Amma, as well as Buddhist, Anglican, Orthdox, Jewish, Shiite and Sunni Muslim leaders in signing a joint declaration at an unusually high-profile ceremony inside the Vatican walls.

The declaration commits the signatories to do everything in their power within their faith communities to work to free the estimated 35 million people enslaved across the world by 2020.

“In the eyes of God, each human being is a free person, whether girl, boy, woman or man, and is destined to exist for the good of all in equality and fraternity,” the declaration read.

Francis has made eliminating modern-day slavery one of the key priorities of his pontificate, inspired by his ministry in the slums of Buenos Aires. Earlier this year, the Vatican launched the Global Freedom Network, a multifaith initiative to encourage governments, businesses, educational and faith institutions to rid their supply chains of slave labor.

One of the network’s founding member, Walk Free Foundation, estimates five countries account for 61 percent of the world’s population living in slavery: India, with an estimated 14.2 million people enslaved, China, Pakistan, Uzbekistan and Russia.

Tuesday’s ceremony, held in a palazzo in the Vatican gardens, added more faith leaders onto the network’s initial roster. Francis sat between Amma, the ebullient Indian guru known for her marathon sessions hugging complete strangers, and the small, bald Sister Chan Khong, the first ordained monastic disciple of Zen Master Thich Nhat Hanh, a Vietnamese Buddhist monk and peace activist.

Alongside them was the Archbishop of Canterbury, Justin Welby, head of the 77 million-strong Anglican Communion, and Grand Ayatollah Mohammad Taqi al-Modarresi of Iran. Also present was a representative of Mohamed Ahmed El-Tayeb, grand imam of Al-Azhar University, one of the oldest and most revered centers of religious learning for Sunni Muslims.

Their speeches were remarkable in demonstrating how different faiths all abhor slavery, but there were also some differences of opinion.

The Anglican members of the network insisted that the declaration refer to “forced prostitution,” to highlight that more and more prostitutes today are victims of human trafficking and are not prostituting themselves by choice. Francis, however, believes no one willingly goes into prostitution.

In the end, the declaration pulled off a compromise with a strategic use of commas to declare that: “Modern slavery, in terms of human trafficking, forced labor and prostitution, organ trafficking and any relationship that fails to respect the fundamental conviction that all people are equal and have the same freedom and dignity, is a crime against humanity.”