The number of employers being prosecuted for hiring illegal workers has risen dramatically.
Figures obtained by the BBC revealed a total of 137 businesses were caught employing illegal immigrants in March and April, the two months after the law was changed.
This is 10 times the number caught in 2007, and more than double the number prosecuted in the previous decade.
Under the new rules introduced in February, employers face fines of up to £10,000 for each illegal immigrant they employ. Persistent offenders also face a jail sentence.
Immigration minister Liam Byrne 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.
“It’s quite clear that this new regime, which is part of a big shake-up of Britain’s border security, is already beginning to work.”
The Conservatives said the government had been too slow in dealing with the issue and the number of prosecutions was still small.