The DTI's analysis, published last week, appeared to favour a change of the current laws in England and Wales as it concluded that there would be an economic benefit from liberalisation. In a section on the impact on small stores, the report states: "The competitive process necessarily involves winners and losers. Indeed, some stores would not be losers unless some of their customers preferred other retailers on price, quality and convenience grounds."
Association of Convenience Stores public affairs manager James Lowman said: "We believe the research commissioned by the DTI does not make a compelling case for change. There is clearly concern about the degree to which this research can be used as the basis for government policy."
Meanwhile, new research from the New Economics Foundation (NEF) on behalf of Spar suggests that small convenience stores could be under threat from any change in the laws, with wider consequences for local communities.
The research revealed that 6.6% of weekly turnover from the Spar network is generated between 4pm and 10pm on a Sunday, the time when larger supermarkets are closed.
The NEF suggested that if just 3% of weekly turnover were lost profits could be hit by up to 28.5%.
Spar UK managing director Jerry Marwood said: "It is clear that if Sunday trading laws were relaxed, many Spar stores would be under threat."
The Deregulate campaign, which has been lobbying for extended Sunday hours for large stores, has suffered a blow as Tesco withdrew its support for the body.