Polish and Latvian illegal workers have been sent home after being discovered working up to 16 hours a day on two Lancaster mushroom farms, reports Steve Dunthorne.
Police and immigration officers swooped early on Friday morning at sites in Quernmore and Galgate.
They were taken to four local police stations, where three Poles later claimed asylum.
As the Citizen went to press, the others had all been returned home.
Immigration inspector Elwyn Soutter, who lead the raid, said the workers had co-operated with police, as had Drinkwater's Mushrooms, the company which owns the farms.
He said the two agencies which employed the foreign workers were now under investigation by the immigration service, though Drinkwater's Mushrooms was not to face charges.
He would not reveal the name of the agencies.
Insp Soutter said: "Drinkwater's Mushrooms were very co-operative in terms of helping us with staff records and that sort of thing.
"Employing a person who does not have permissions to work in the United Kingdom is an offence.
The evidence we have at the moment suggests they were actually employed by the agency, in that case the offence would be committed by the agency."
A total of 33 foreign nationals, all but one of them from Poland, were discovered.
The majority of them were young women aged 18 to 30.
Some were working on visas, which had expired, others were on six-month tourist visas, which do not allow them to work.
Two pretended to be Spanish, while the Latvian had a forged visa.
Some had been in the country for as long as four years.
"I cannot confirm what their wages are, but their hours of work were from 6am in the morning to 9 to 10pm at night," Insp Soutter added: "One assumes they did that because they had to do it.
To someone from Eastern Europe, the wages would probably be attractive."
The workers were living in houses and caravans, rented by Drinkwater's Mushrooms, close to the site.
"The conditions were a bit spartan but they were not squalid," said Insp Williams.
"The workers had no transport off the isolated site, apart from a minibus to take them shopping at the weekend."
Working without permission carries a maximum sentence of six months in prison and a £5,000 fine, but Insp Soutter said charges were rarely brought for first offences.
"We have done a number of similar operations in Lancashire," he added: "It is quite common for foreign workers to work on farms - we have done four or five similar operations in the Southport area."
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