A growing number of businesses are being prosecuted for employing illegal workers, according to research by the BBC.

The organisation reports that 137 businesses were caught breaching new rules in January and February this year, 10 times the figure for the whole of 2007.

Companies can now face fines of £10,000 for each illegal worker and repeat offenders can face prison. Fines in the region of £500,000 have been imposed in the last two months.

"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," immigration minister Liam Byrne told the BBC.