Gwyneth Dunwoody has agreed to introduce a Private Member's Bill to ban large stores opening on Christmas day.

More than 100 MPs have pledged to back the bill which is being backed by shop workers union Usdaw. The legislation would be aimed at stopping stores over 3,000 sq ft from trading. Smaller convenience stores would retain the right to open.

The Crewe and Nantwich MP said: "I have chosen the protection of Christmas Day, because I believe it strikes at the very heart of family-friendly employment. Britain is fast turning into a 24-hour, 365-day per year society and I think it is time to apply the brakes.

"The vast majority of shop workers are parents and I believe they should be allowed to be at home with their children on Christmas Day. After all, they do work extremely hard throughout Christmas and New Year period and I think they deserve at least one guaranteed day off."

Usdaw General Secretary, Bill Connor, said: "This year saw more shops open on Christmas Day than ever before. Our members in the retail industry are under increasing pressure to work more unsocial hours. Since the introduction of the Sunday Trading Act 1994 we have seen retailers move to 24-hour opening, Bank Holiday opening and browsing time on Sundays."

Leading chain stores defied critics by opening some branches on Christmas Day. Sainsbury's, Woolworths, Budgens and the Co-op used volunteer staff to test customer demand.Woolworth's opened three of its 800 stores in largely Asian communities. Defending the decision the company said it was in recognition that Britain is an "increasingly multi-cultural society" with many people who do not celebrate Christmas. It added that staff who worked on Christmas Day were volunteers. Sainsbury said the openings were for people who had forgotten last-minute items but it was mainly for motorists and part of an ongoing trial of shops on petrol stations.