Shopworkers' trade union Usdaw wants new laws banning big stores from opening on Christmas Day implemented as soon as possible.

Labour MP Kevan Jones' Private Member's Bill, which prohibits stores larger than 280sqm from opening on Christmas Day has now received Royal Assent.

The responsibility for implementing the Christmas Day (Trading) Act 2004 rests with the Trade and Industry Secretary, Patricia Hewitt.

Usdaw is now urging Ms Hewitt to bring the law in before December 25.

John Hannett, Usdaw's general secretary, said: "This law means shopworkers can concentrate on enjoying Christmas, at home with their families, without the fear of being forced to work."

A final decision on the timetable for implementing the law is expected within weeks.