Employment relations minister Gerry Sutcliffe

Former employees will be able to claim back-salary from previous employers who failed to pay the minimum wage under a new law now coming into force.

Under the National Minimum Wage (enforcement notices) Act, Inland Revenue staff will be able to force firms to pay arrears to both former and existing workers employed since August 2002 who have not received the £4.20 per hour.

The amendment follows an employment tribunal last year, which revealed the loophole in the 1998 act.

Employment relations minister Gerry Sutcliffe said the move showed that the government was not complacent in enforcing the rules and would tighten them up where necessary.

"The government is determined to make sure all workers, including those who have left for new jobs, get what they are owed," he said.

The move was welcomed by the TUC.

"The minimum wage is a useful protection for low paid workers and must be fully enforced," said general secretary Brendan Barber.

"Our experience has been that many low paid workers only have the confidence to complain about underpayment after they have left the offending employer.

"The government has already recovered £13 million for workers cheated out of the minimum wage. This law will help them keep up the pressure and ensure that there is no hiding place for bad bosses."

In October, the minimum wage will increase to £4.50 for those aged 22 and over, while those workers aged between 18 to 21 will see an increase from £3.60 to £3.80.