The minister responsible for an overseas worker program that led to scores of people living in one Tasmanian house has refused to answer questions about the program.

Key points: The local mayor says the council wasn't consulted when the program permit was issued but is expected to deal with the fallout

The local mayor says the council wasn't consulted when the program permit was issued but is expected to deal with the fallout There are regular reports about seasonal workers living in poor conditions, unions say

There are regular reports about seasonal workers living in poor conditions, unions say The federal department in charge of the program says it will investigate allegations of mistreatment

Latrobe Council said it issued an emergency order to evacuate up to 70 residents, understood to be from Tonga, from a five-bedroom house at Shearwater, east of Devonport.

The Australian Workers Union said it was one of the worst cases of exploitation it had seen, claiming as many as 77 people were living in "slum-like" conditions and each paying up to $130 a week in rent.

Following the evacuation, Mayor Peter Freshney said it was council's expectation that "there will be an immediate and long-lasting improvement in the way in which the Federal Government's Seasonal Worker Program is administered".

The workers had been picking berries for horticulture giant Costa Group, which said "substandard accommodation" had been provided for up to 67 workers by a third-party labour supplier.

Costa Group has subsequently issued a breach-of-contract notice with the labour supplier and apologised to the workers.

Robert Flanagan, assistant secretary of the AWU in Tasmania, said problems with the Seasonal Worker Program went beyond this incident.

"We're regularly being contacted by people on the program, and also others that come in on working visas, about conditions they're subject to, particularly in the horticulture sector," he said.

"I understand the other branches of the AWU are receiving the same sort of feedback.

"The Federal Government has sanctioned a systematic abuse of human rights, and there needs to be immediate action by the Government to implement a strict auditing process so this exploitation stops, right now."

Onus on council to enforce regulations

The office of Employment Minister Michaelia Cash would not respond to questions about the program put by the ABC this week.

Instead, a spokesperson for the Department of Employment, Skills, Small and Family Business provided a written response.

"The Government takes all allegations seriously, and the department will investigate allegations of mistreatment of seasonal workers under the program," it said.

"All approved employers under the Seasonal Worker Program are to ensure that accommodation is safe and secure and is fit for occupation and use for each seasonal worker employed.

"[Employers must also] comply with any work health and safety legislation or state and territory government and local government legislation and codes that may apply to such accommodation.

"Whether the accommodation meets the council regulations is a matter for the relevant local council."

'No checks and balances'

Mr Freshney said the council had not been consulted when the worker program permit was approved, yet it was expected to deal with the fallout.

"The flaw, I believe, in the policy, is the approved employer makes the declaration that the properties are compliant, but there are no checks and balances in the process where local government can confirm that is the case," he said.

"That is something we'd like to see changed, that's for sure."

The National Farmers' Federation said it was the responsibility of "all stakeholders involved in the employment of farm workers to, as far as possible, satisfy themselves that workers are being treated in a way that is lawful and ethical".

"Farmers continually report that a lack of housing in regional towns and villages for seasonal and itinerant workers hinders their ability to attract workers," NFF chief executive Tony Mahar said.

Opposition spokesman Brendan O'Connor called on Prime Minister Scott Morrison and Senator Cash to investigate workers' living conditions.

"The Government needs to explain what measures they are putting in place to ensure other workers on the program are safe," he said.

Meanwhile, Greens agriculture spokeswoman Janet Rice said it was hard to know if this was an isolated incident.

"The fact it keeps happening is a real worry, and the problem is it tars everybody with the one brush," Senator Rice said.

The department spokesperson said the Government had zero tolerance for the exploitation of workers.

Numbers not clear

Wages earned by Tongans on the Seasonal Worker Program now exceed the total value of Australian aid sent to Tonga and Tongan exports to Australia combined.

Sione Vaka from Tonga's Ministry of Internal Affairs, who is a liaison officer with the program, told the ABC he had visited the Shearwater property.

"I am confused about the news saying 70 people in five bedrooms — that is not true ... the house was renovated to accommodate 17 people and it was approved from the department," he said.

"There are three separate houses; one main building and two small houses on the side."

Mr Vaka said the workers had not complained about the conditions and the matter "was between the landlord and the council".

The workers were surprised to be moved from the house, he added.

Mr Vaka's comments came as the AWU complained about another property linked to the program providing "squatter-like conditions".