Although Sunday is one of the top three trading days for Sainsbury's, the supermarket giant's chiefs believe the benefits of extra sales from additional opening hours may not outweigh the extra costs it would have to absorb from staffing, distribution and its supply chain.
Sainsbury's stance is in marked contrast to other retail big guns such as Tesco, Asda, Ikea and B&Q - all of which have been lobbying hard for opening hours to be extended.
A Sainsbury's spokeswoman said: 'We are not part of this current group of retailers looking for opening hours to be relaxed. Our customers tell us they are happy with our opening hours and we have not had any demand to change them.'
Sainsbury's, led by Justin King, pays shopfloor staff an extra flat rate per hour on Sundays and extended hours would impose a further financial burden.
A Sainsbury's checkout assistant earning£5.39 an hour during the week receives£7.92 an hour on Sundays.
The existing Sunday trading laws, introduced in 1994, allow stores of more than 3,000 sq ft (280 sq m) to open for up to six hours. However, earlier this month trade and industry secretary Alan Johnson asked the DTI to look into the benefits of relaxing Sunday trading laws, following pressure from lobby group Deregulate. Its chairman David Ramsden, one of the original co-ordinators of the Sunday shopping campaign in the early 1990s, is leading calls for opening hours to be extended.
Shopworkers' union Usdaw and the Association of Convenience Stores both oppose relaxation of the existing Sunday trading hours.