Rogue employers are getting away with paying over 300,000 people across Britain - the population of Nottingham - less than the minimum wage, researchers said yesterday.

Think tank Centre for London and charity Trust for London called for tough new regulation to punish the offenders - many of whom are care agencies taking government cash.

The groups said fines should be higher and councils should be given more powers to bring such firms to book.

The researchers also called for firms to be named and shamed and demanded that ads for unpaid internships be banned.

The main culprits include employers in the catering, agriculture, cleaning and food processing industries, where oversight is lax and workers often marginalised.

Social care was highlighted as the sector where the biggest amount of offending occurs as most carers "do not get paid the national minimum wage for the time they have to spend travelling between clients."

To disguise the rip-off agencies issue "labyrinthine payslips detailing pay for every minute worked."

East Yorkshire carer Jane Smith provides home care for the elderly.

She is employed on a zero-hours contract and is subject to a confusing pay scheme that leaves her "struggling" at the end of every month.

"They rota half-hour unpaid breaks that they know we have to use to travel to the next client," she told the Morning Star. "I don't feel valued at all."

Unison says 58 per cent of its care workers are paid less than the minimum wage because of the agencies' travel scam.

The report concludes that the situation "threatens to compromise the quality of service in a sector that comprises over two million workers."

TUC general secretary Frances O'Grady backed the call for urgent action.

She said: "HM Revenue and Customs staff regularly recover more than £3 million a year for workers on illegal poverty pay. It is clear that far too many unscrupulous bosses are still getting away with ignoring the minimum wage."