Shadow foreign secretary Lisa Nandy has said in an interview that it would be «wrong» to relax Sunday trading laws.
The government reportedly plans to suspend the laws for a year, in a bid to stimulate the economy after the coronavirus crisis.
But doing so may not bring in more sales, Ms Nandy told the Andrew Marr show on BBC One.
«I’m not at all convinced that this will actually help to get the economy back on track,» she said.
Since 1994, trading laws have allowed smaller shops to open all day on Sundays in England and Wales. Larger stores, such as supermarkets or department stores, may open for six hours between 10:00 and 18:00.
«We’ve just been applauding our frontline workers, supermarket workers are amongst those,» said Ms Nandy.
«They are deeply worried about what this all means for them in terms of time with their families.
«This could hit our high streets very hard as well at a time they are really struggling with coronavirus – I just think this is the wrong thing to do.»
The proposed relaxation of the rules were reported by the Times newspaper on Saturday.
Reforming Sunday trading laws
Plenty of attempts have been made in recent years to relax the rules further, but have met resistance from religious leaders and small business leaders, who fear it would hand larger shops an advantage in gaining more sales.
The last attempt to overhaul the rules was in March 2016, when David Cameron’s conservative government was defeated by 317 votes to 286.
The government had hoped to relax existing restrictions on Sunday trading, which limit large shops to opening for a maximum of six hours, by devolving responsibility to local councils.
But their plans were thwarted by an unlikely alliance of Labour, the SNP and Conservative backbenchers.
Proponents of Sunday shopping argue that restrictions on opening hours are anachronistic and out of kilter with the 24/7 economy in goods and services that people have come to expect and rely upon.
Meanwhile, others oppose relaxing Sunday trading laws on religious grounds, as well as concerns about the impacts it would have on small businesses and on the families of shop workers.