Several companies, including Indian restaurants, have been fined over pound 500,000 for employing illegal immigrants from India, Pakistan and other non-European Union countries.
The fines were imposed after a tougher law came into effect from February, official figures reveal.
As many as 137 companies, many of them Indian restaurants struggling to employ chefs, have been caught and fined for employing staff illegally. Employers face a fine of pound 10,000 for each illegal immigrant they employ.
The figure is 10 times higher than the total for the whole of 2007, and more than double the number of companies prosecuted in the last decade, the figures say.
In the last two months the number of enforcement operations has risen by 40 per cent and fines of roughly pound 500,000 have been handed out. Persistent offenders also face a jail sentence.
In an enforcement operation covered by the BBC, 60 UK Border Agency officers raided a chicken processing factory in Derbyshire, following police intelligence suggesting that illegal immigrants were working there.
They found a large processing room with 56 workers, all from overseas, and after several hours of questioning determined that 22 of the workers were illegal immigrants from countries including Afghanistan, Pakistan and India.
Liam Byrne, the Immigration Minister, told the BBC: "There are dodgy employers out there who are trying to undercut their competitors and drive down British wages by employing people illegally, so we've come up with this new way of taking much faster on-the-spot action".