Proposed laws to shine a light on modern slavery may be too weak to have a real impact, according to the Law Council of Australia.

Key points: There are no penalties for companies that fail to comply

There are no penalties for companies that fail to comply Government believes making the companies' reports public enables consumers to boycott businesses

Government believes making the companies' reports public enables consumers to boycott businesses Around 25 million people world-wide are exploited in slave-like conditions

The country's largest companies would be required to report annually on what they are doing to make sure slave labour is not part of their operations or supply chains.

It would apply to businesses with revenue of more than $100 million a year and the reports would be made publicly available.

But there are no penalties for companies that fail to comply, other than public exposure of their failure to do so.

"If we're going to have an effective piece of legislation, let's give it some teeth," the Law Council's president, Morry Bailes, said.

He will give evidence today to a Senate inquiry examining the Modern Slavery Bill.

"A $100 million turnover is only going to capture a very few companies in Australia," Mr Bailes said.

"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 believes making the companies' reports publicly available will allow consumers to boycott businesses if they are not addressing modern slavery.

Mr Bailes insists financial penalties will be more effective than potential public backlash in ensuring companies act.

"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."

Thousands of Australians endure slave-like conditions

Modern slavery covers crimes such as forced labour, wage exploitation, involuntary servitude, debt bondage, human trafficking, forced marriage and slavery-like exploitation.

The United Nations estimates 25 million people around the world are exploited in slave-like conditions, often driven by global supply chains.

There have also been estimates of around 4,000 Australians enduring slave-like conditions.

The assistant minister for home affairs, Alex Hawke, introduced the bill to the House of Representatives at the end of June.

"This significant initiative will shine a light into the shadows of global supply chains where modern slavery thrives," he said at the time.

"The Government will also lead by example by considering possible modern slavery risks in our own procurement."

Mr Hawke said the Government would consider making changes to the bill.

It may have to, with the Opposition's push for tougher penalties for companies.

Mr Hawke is currently overseas and unavailable for comment.

"It's important to remember we're talking about slavery here," Clare O'Neil, Labor's shadow minister for justice, said.

"This is one of the most grave human rights abuses that can occur — to take away someone's liberty.

"I don't think it's too much to ask that Australian companies report on the things they're doing to tackle this problem.

"There has to be penalties attached to that, it's not optional to abide by the law for anyone else in this country and companies shouldn't be given any type of different or special treatment."

The Opposition is also calling for an anti-slavery commissioner to be appointed — a move the Law Council backs.

The Law Council has also called for a compensation scheme for Australian victims of modern slavery.