At least 1.5 million workers, mainly in the hospitality industry, are still being cheated out of the national minimum wage (NMW) by rogue employers according to research conducted by the Trade Union Congress (TUC).

The report, called Enforcing the National Minimum Wage, claims that workers most likely to be affected are in London, the North West, Merseyside and the South East, and are employed in hotels, bars and restaurants. Although last year £3.9m was recovered from law-breaking bosses, the TUC estimates that hundreds of thousands of workers are still taking less money home than the law stipulates.

TUC general secretary Brendan Barber said: 'The Revenue and Customs teams responsible for enforcement are doing a good job and have already retrieved millions of pounds from employers failing to pay the NMW. "But TUC research suggests that there are at least 1.5 million workers across the UK who are still losing out. This shows the need for continued public funding for the National Minimum Wage helpline which allows people to make a complaint about an employer they suspect is not paying the minimum wage.

"There must be no hiding place for rogue bosses. Our guide aims to make it easier for unions and advice agencies to root them out and ensure everyone gets the wage to which they are legally entitled." The report is the third edition of the enforcement guide, published in 2001, which sets out how unions and advice workers can make sure everyone earns the NMW.

For over 22 year olds the NMW is £5.73; £4.77 for 18 year olds; and £3.53 for workers under 18.