An investigation has been launched into labour-hire providers and farmers suspected of illegally exploiting workers in "Australia's salad bowl".
Officers from federal government departments this week made surprise visits to seven operations around Gatton, west of Brisbane in the Lockyer Valley, including fruit and vegetable farms producing broccoli, onions, pumpkins and shallots, after receiving an undisclosed number of tip offs from the community.
The Australian Taxation Office (ATO), Fair Work Ombudsman (FWO) and Department of Home Affairs said they were investigating operators to ensure they were complying with tax, super, workplace and immigration laws.
Inspectors and officers spoke to workers, managers and employers, requesting a range of records.
The operation comes after the United Nations Special Rapporteur on contemporary forms of slavery, Tomoya Obokata, said he was "seriously concerned" by the treatment of temporary migrant workers in Australia after a recent official visit.
ATO assistant commissioner Tony Goding said the tax office would not tolerate employers who were not doing the right thing.
"We have zero tolerance to this type of behaviour in the community — it's just not on," he said.
"Businesses that engage in the shadow economy are deliberately undercutting their competitors, gaining an unfair advantage in their industry and stealing from their employees' futures."
Shadow economy behaviours include paying workers cash in hand to avoid obligations, paying wages below award rates and not paying workers' other entitlements.
The ATO receives about 50,000 tip offs a year on shadow economy behaviour.
Officials will review any evidence collected and decide if legal action or education is required.
Mr Goding said the ATO recognised most employers were honest and would do the right thing, "but with any industry, there will always be, unfortunately, a few bad apples".
The operation is part of a wider response by the government's Shadow Economy Taskforce, with the tax office promising "more activity by the ATO in the community in the months to come".
Fair Work Ombudsman Anna Booth said holding employers to account in the agriculture sector was a priority area.
"In recent years, we have found that non-compliance in the agriculture sector has been disproportionately higher among labour hire employers," she said.
Ms Booth urged farm workers with concerns about their pay or entitlements to come forward and directly seek assistance, saying they could remain anonymous.
Department of Home Affairs field operations commander Ben Biddington said Australia would not tolerate exploitation and abuse of its visa programs.
"Migrant workers play a key part in the economy, particularly in remote and regional communities [and] there is no place in Australia for employers who exploit them," he said.
Rachel Chambers, chief executive of state horticultural group Queensland Fruit and Vegetable Growers (QFVG), said she supported investigations into any allegations.
"I have been privy to accidental or lack of knowledge of processes that have been easily fixed up, but as far as intentional exploitation — that is not within my personal experience," she said.
"We certainly support the relevant authorities to get in there and investigate anything that comes to their attention."
Ms Chambers said industrial relations in horticulture were often more complex than other agricultural sectors and keeping up with constantly evolving legislation was part of the challenge.
"With horticulture, the actual workforce is so complex," she said.
"It's not about having a workforce that are all full-time, Monday to Friday.
"You might have three or four different labour components, they all may work different hours, they all may only work for one day, they might work casual hours, they might work overtime, they might have time off in lieu."
Ms Chambers said best growers who were trying "to do everything 1,000 per cent right" threw all of their effort into compliance.
"For us, the question is, are we getting better at complying? We absolutely are getting better at complying," she said.
"What is unfortunate, though, for our industry, is that the goal posts keep changing.
"[With] industrial relations regulations over the last 18 months, there's been a huge element of reform that is very hard to keep up with in such a complex industry."
Ms Chambers said QFVG would continue to educate and support its growers to the best of its ability.