Mr Forrest has joined forces with faith groups calling for new legislation to outlaw modern slavery and forced labour, which is on the rise.

Writing on behalf of 18 national faith leaders, James Condon from The Salvation Army, who is chair of the Australian Freedom Network, has called on the federal government for an act of Parliament to discourage slavery-like conditions.

"As faith leaders united against modern slavery, we express our concerns about the welfare and human rights of thousands of migrant workers who are either at risk of or are experiencing forced labour in Australia," the letter says.

Mr Forrest, chairman of Fortescue Metals Group, said it was critical for businesses around the world to look for slavery within their operations.

"But not all business leaders will come willingly to this issue," he said.

"To this end, all governments have a crucial role to play in ensuring there are laws that require companies to look for and report instances of slavery, as a means of addressing the greatest human rights challenge of our era."

The Fortescue Metals Group was shocked to find evidence of slavery within its supply chain in 2012, he said.

Fortescue introduced a zero tolerance approach to slavery in its supply chain. 

British example

David Cooke, the chief executive officer of Konica Minolta, said the introduction of a Modern Slavery Act in the UK had brought the issue to public attention.

"The federal government must look seriously at following its UK counterpart," Mr Cooke said.

"I believe every business should take responsibility for ensuring their supply chain is free of modern slavery and other forms of human rights abuse."

An estimated 4300 Australians and 45.8 million people in 167 countries are in some form of modern slavery.

Amy Sinclair, from the Australian Lawyers for Human Rights, said worker exploitation scandals had demonstrated the need to clean-up supply chains.

"A Modern Slavery Act for Australia would provide an essential tool to drive transparency and end the exploitation of vulnerable workers, both here and overseas," she said.

Foreign Affairs Minister Julie Bishop was among federal MPs attended a round-table discussion on human trafficking and slavery late last month.

Exploitation embedded

Jenny Stanger, who manages the Salvation Army's Freedom Partnership to End Modern Slavery, said exploitation is embedded within the Australian economy.

She said federal ministers have only announced non-regulatory and non-legislative measures in response to the problem.

"This means that the risk of slavery in supply chains will continue to be voluntarily self-managed rather than an obligation for business. This is despite the fact that our region, the Asia-Pacific, has the highest prevalence of slavery in the world," Ms Stanger said.

Melbourne Anglican archbishop Philip Freier said the eradication of modern slavery needs to be a national priority for government, business and society.

"It's only by working together that we can succeed in abolishing slavery," he said.

The UK Modern Slavery Act 2015 includes a public obligation on large businesses to report on steps they have taken to eliminating slavery and human trafficking in their businesses and supply chains.

Stuart McMillan, president of the Uniting Church in Australia, said pressure for cheap goods and services, a growing workforce of temporary migrant workers and unregulated labour hire can could potentially harbour growth in modern slavery.

"As consumers we do not want to inadvertently contribute to the profits of slavery. Increased transparency in supply chains means there is no longer an excuse to say we do not know if there is slavery in the supply chain," he said.