Authorities detained several alleged unlawful foreigners yesterday in raids on Neerabup market gardens as part of a continuing crackdown on an alleged multimillion-dollar crime syndicate.
Police are targeting other businesses they suspect are using illegal overseas workers allegedly provided by the accused crime ring.
They yesterday put employers on notice that they faced fines or jail if they employed or referred workers who did not have valid visas.
Acting Det-Supt Chris Adams said employers needed to check whether foreign staff were allowed to work, regardless of whether they were sourced directly or via a contractor, labour hire or referred from another organisation.
The Immigration Department will deport 120 illegal workers and visa over-stayers already caught after raids on dozens of Perth properties during the long-running operation, including at a Carabooda compound owned by two brothers accused of running a criminal empire.
A spokeswoman for Immigration and Border Protection Minister Scott Morrison said the 120 men and women from Malaysia, Indonesia and Vietnam were at immigration detention centres in Northam and Perth.
Federal police claim the alleged syndicate developed a sophisticated money-laundering scheme involving multiple companies, enabling underpayment to foreign workers while retaining commissions and allegedly avoiding tax payments.
The illegal workforce was allegedly created by recruiting foreigners who entered Australia lawfully but had overstayed their visas or did not have work rights.
Mr Morrison's spokeswoman said civil penalties ranged from $3060 to $76,500 per illegal worker.
"Businesses convicted of knowingly or recklessly allowing or referring an illegal worker to work face fines of up to $20,400 and two years' imprisonment, while companies face fines of up to $102,000 per illegal worker," she said.
Suresh Rajan, from West Australians for Racial Equality, said the Immigration Department had failed to monitor closely the operations of businesses using foreign labour.
He expressed concern that all 120 people were being detained and deported without having the opportunity to stay legally despite allegations they were exploited and virtually treated like slaves by criminals.
A man who claimed he once worked for a vegetable grower who used foreign workers from the TLF Exports compound alleged they told him they were like prisoners because they were never given enough work to get out of debt.
The man, who did not want to be named, said the market gardener he worked for knew some workers were illegal but believed because he paid the hire firm award rates it was not his responsibility.