The Malaysian national that helped Fairfax Media undercover exploitation in Victoria's fruit picking industry has today told a modern slavery inquiry that workers were "brainwashed" by religion and trapped in an inescapable cycle of debt.

Having flown back from Malaysia to give evidence, Saiful Hasam spoke of the “thousand sad stories” he heard during his two weeks at a fruit farm in northern Victoria.

Based on my observations, they are being brainwashed using religion.

Mr Hasam claims fruit pickers were promised high incomes if they moved to Australia. Instead, they received a pittance on arrival and were made to stay in overcrowded homes with unreasonable rent.

A reporter with Utusan Malaysia, Mr Hasam went undercover last year to document the experiences of those suffering in the system.

His work in the Fairfax Media exposé helped drive the introduction of a modern slavery act in Australia, which has been tabled as a recommendation by the Joint Standing Committee on Foreign Affairs, Defence and Trade.

According to The Guardian, Mr Hasam was paid $110 for 24 hours work over four days. About $80 went to pay rent in a small home he shared with 11 other workers, mostly from Malaysia. He was short-changed $10 by his contractor, leaving him with just $20.

“The story is basically the same, the sad story,” he said.

“A thousand sad stories, they are basically the same story. They are struggling. For the newbies, they are very struggling and keep thinking, ‘Today I have to settle how many trees just to pay rental. After finish that part, then we are struggling to collect enough money for the food’.

“Sometimes, based on my experience, it’s just enough for food and rental … This is grossly unfair for the workers, because they are very hard-working.”

Asked whether the workers raised concerns with their employers, Mr Hasam said they were "brainwashed" to accept the circumstances.

“Based on my observations, they are being brainwashed using religion,” Mr Hasam said. “The house leader always say, ‘OK, please be patient, this is your test, coming to Australia, and one fine day you will get enough money. This is normal for everybody, and even me myself go through this process’.”

In August, justice minister, Michael Keenan, announced plans to impose a legal requirement for companies with a turnover larger than $100 million to file a public modern slavery report each year.

Tania Chapman, the chairwoman of the industry body Citrus Australia, warned against painting all farmers and growers with the same brush. She insists the majority are doing the right thing.

“We have unfortunately seen people abuse the 457 visa scheme only to the detriment of our country’s other growers that rely heavily on this type of labour,” Ms Chapman said.

“This abuse of power has left a black mark on our industry with both media and outside organisations labelling farmers as complacent or indeed negligent when it comes to supporting the harvest labour force, with words such as slave labour being introduced.”