The Law Council says proposed laws to shine a light on slavery could be too weak.

The Modern Slavery Bill would force Australia’s largest companies to report annually on measures to ensure slave labour is not part of their operations or supply chains.

The new requirement is proposed for businesses with revenue of over $100 million a year.

While the reports would be made publicly available, there are no real penalties for companies that fail to comply.

“If we're going to have an effective piece of legislation, let's give it some teeth,” Law Council of Australia president Morry Bailes has told the ABC.

“A $100 million turnover is only going to capture a very few companies in Australia.

“It is higher, for example, than the equivalent legislation in the UK.

“We would recommend that the threshold should be $60 million.”

The Federal Government says having the reports publicly available will allow consumers to punish companies if they choose to.

Mr Bailes says financial penalties will be more effective.

“Reputation can be re-gained — what really matters is proper penalties and sanctions,” he said.

“Without sanctions and without penalties, mere reputational harm to companies is insufficient to stop that type of behaviour.”

A recent UN report found there are about 15,000 people living in some form of slavery in Australia.

Australia’s slave practices occur most frequently in the hospitality, construction, agriculture and sex industries, but also in private homes and within families in the form of forced marriage.