VATICAN CITY -- Christians and Muslims have joined to try to help free millions of men, women and children held in modern-day slavery, forced to work as maids, prostitutes, child soldiers and manual labourers.

The Global Freedom Network launched Monday at the Vatican aims to eradicate slavery by encouraging governments, businesses, educational and faith institutions to rid their supply chains of slave labour.

The initiative is the brainchild of billionaire Australian mining magnate Andrew Forrest, who founded the Walk Free Foundation in 2012 to mobilize a grass-roots movement to end slavery.

Forrest, ranked 270th on Forbes' list of the world's richest people, used personal contacts to bring the 1.2-billion strong Catholic Church, 85-million strong Anglican Communion and al-Azhar university in Cairo, the world's foremost seat of Sunni learning, on board with the initiative.

Representatives from all three gathered Monday at the Vatican to sign an agreement to launch the project, which will be based at the Vatican and have a chief executive responsible for implementing a five-year business plan. Objectives include getting the G20 to condemn modern-day slavery, persuading 50 major corporations to commit to slavery-proofing their supply chains and convincing 160 governments to endorse a seven-year, $100 million fundraising effort to implement anti-slavery programs globally.

In an interview, Forrest said it makes financial sense for countries to rid themselves of slave labour.

"We have absolute economic proof that once you take slavery out of a community, that community grows and grows and grows," he said.

The Walk Free Foundation in 2013 published the "Global Slavery Index," a country-by-country breakdown which found that some 29.8 million people were currently enslaved around the globe: child labourers harvesting cocoa in Ivory Coast, women sold for sex in Moldova, and Haitian children trafficked and forced into begging. Everyday items used in the developed world -- soccer balls, bricks, diamonds and flowers -- are often produced or extracted using slave labour, the report said.

The presence of al-Azhar at the Vatican for the launch was particularly significant given that relations between the Holy See and al-Azhar collapsed during Pope Benedict XVI's papacy. Pope Francis has spoken out about human trafficking and was behind a November 2013 Vatican conference on modern-day slavery.

The International Labor Organization has estimated that trafficking in human beings -- just one segment of the slavery industry -- generates $32 billion in profits every year.

Forrest said representatives of other faiths were welcome to join the project's governing council.