Children’s health and education are being sacrificed to fuel the boom in Sunday opening for shops, according to critics of the proposals published by the Department of Health.

There will be no increase in the weekly total of 20 hours that children can work. But with an estimated 60,000 already employed outside the law, it is feared that an official go-ahead for Sunday working, expected next Spring, will swell their ranks further.

There is increasing concern that badly paid youngsters are replacing full-time adult labour. There is also fresh evidence that most child employment is conducted illegally, with local authorities unable or unwilling to monitor the situation.

The Trades Union Congress is about to publish a national survey showing that many child workers are too tired for school or homework. Another new survey to be published after Christmas has found 96 per cent of child employees operating illegally, without a permit from their local education authority. Seventy per cent of child workers in Blackburn covered by the University of Liverpool survey were working for under #163;2 an hour; some earned as little as 35 pence.

Last week a study by Unicef suggested that 26 per cent of 11-year-olds in Britain are working.

The giant GMB union is so concerned that it has launched a pilot recruitment project in Newcastle, signing up 200 schoolchildren into free membership in an attempt to protect them against exploitation.

It is against this background that the Department of Health has backed proposals abolishing the current two-hour working limit for children on a Sunday. Under the draft plans, 13 and 14-year-olds can work for five hours; 15 and 16-year-olds can work for eight hours.

The DoH is almost certain to press ahead, describing this option as “strongly favoured” in a response to the European Union’s working hours directive, which seeks to limit adult working hours to 48 hours a week. In theory children’s hours are governed by local authority byelaws. In practice the councils follow DoH guidelines. New model byelaws are expected from the Department in the spring.

At present, a 15-year-old can work for two hours on school days and Sundays, and eight hours on a Saturday. Opponents insist that increased flexibility on Sunday will encourage more children to work longer hours in total.

“Two hours on a Sunday is quite enough for a young person, ” said Joan Lestor, a prominent Labour MP and a long-standing campaigner on children’s issues. “The sad thing is that some parents will welcome it because it’s the only source of money. We should be providing jobs for adults.”

In theory children must have work permits from their LEAs. In practice the system is ignored. A report last year from the GMB found that seven out of eight children who are working - roughly 600,000 in all - are doing so illegally. Only 15 of 108 LEAs maintained child employment officers.

Sandy Hobbs, an authority on child employment at the University of Paisley in Scotland, said there is clear evidence that children who work 10 hours or more a week do less well at school.

Chris Pond, director of the campaigning Low Pay Unit, said “Ministers are displaying a wilful complacency towards both the risks to health and safety and the educational disadvantage faced by this most vulnerable section of the workforce.” His research suggests that one in three child workers has been injured at work.

Don Jones the child employment officer with Wolverhampton said, “Even if you have said a child can work five hours on a Sunday, you have no guarantee it’s going to be five hours.”