The number of illegal workers arrested in Kent has shot up by nearly 50% in the last year, figures reveal.
Last year nearly 370 employees were held by police for having the wrong paperwork in the county, up by 47% on the previous year.
That follows a huge fall, from 647 illegal workers in 2008.
Worst culprits for employing foreign workers without the correct documents were restaurants.
Figures obtained by KentOnline show that in 2008, nearly 650 illegal workers were arrested in the county.
But, after a drop, last year there was a considerable increase - from 248 to 364.
Businesses can be fined up to £20,000 per person for employing illegal workers but over the same period the number of businesses issued with penalties has fallen from 118 to 53.
And the total amount collected in fines has also plummeted from £1,108,750 in 2008 to £367,500 in 2013.
Jo James, chief executive of Kent Chamber of Commerce has questioned what the reduction in arrests really means.
She said: "Employing illegal workers gives businesses an unfair advantage; they often pay illegal workers less, which enables owners to charge less for goods and services or just keep the difference and make loads of profit.
"Much of the money does not go back into the local economy as a big reason people come to the UK to work illegally is to support a family back home."
Arrest numbers dropped from 647 in 2008 to 549 in 2009, then in 2010 the number fell to 341, then 217 in 2011.
But in 2012 arrests went up slightly to 248, with a further increase to 364 in 2013.
The sector that has seen the highest number of arrests by far is catering, with 450 illegal workers collared in restaurants and takeaways since 2008.
Jo James said: "The last few years have seen a big growth in non-British restaurants as people's tastes have changed.
"People will only pay so much to eat out and it is costly to stay in the high street with high business rates and high rents. There is a finite amount people can charge so they might look to make savings in other ways."
Martin Couchman, deputy chief executive of the British Hospitality Association, said: "The fact the percentage of workers arrested in restaurants and takeaways does not surprise me.
"The process is intelligence-led, and in these places members of the public may be aware of illegal workers working there. If someone is working in an office it's not as clear to so many people.
KentOnline has contacted the Home Office to ask for an explanation of the figures and we are expecting a statement later today.
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