Trade and Industry secretary Alistair Darling announced on Jan 9 that employers could be fined £200 for every worker they had underpaid.
He said: "Workers have the right to a decent minimum wage and we are determined they get it. To those employers avoiding the minimum wage the message is: don't pay it and you'll pay the fine."
Employers already have to pay back arrears they owe workers, but this step means those who refuse to pay their staff within seven days of enforcement will be fined. Those who fail to pay the minimum wage could also be hit with a criminal record and a £5,000 fine if prosecuted.
Paymaster General Dawn Primarolo said: "The vast majority of employers are honest and scrupulous but this new measure will put further pressure on those rogue employers who continue to flout the law."
The minimum wage rose from £5.05 to £5.35 an hour for workers aged 22 and over, from £4.25 to £4.45 an hour for 18 to 21-year-olds and from £3 to £3.30 an hour for 16 to 17-year-olds on Oct 1 2006.