An estimated 4,300 people are now enslaved in Australia, a parliamentary inquiry has been told, but Australian companies are also linked to slave-like supply chains overseas, where tens of millions work in bondage.

Thirty million people are estimated to be held in slavery or slave-like conditions across the Asia-Pacific region: major trading partners and supply countries such as India, China and Bangladesh have some of the largest slave populations in the world.

The Australian parliament is now evaluating a modern slavery act, based on the UK’s 2015 legislation.

Speaking in Sydney on Wednesday, the UK’s independent anti-slavery commissioner, Kevin Hyland, said Britain’s Modern Slavery Act had proven a powerful law enforcement tool that had profoundly changed the lives of slavery victims.

Since the introduction of the legislation, there had been a 63% increase in the number of victims coming forward – to more than 4,000 referrals last year – and a 77% increase in convictions.