Shop workers are being put at greater risk of violence, verbal abuse and coronavirus infection by pubs shutting at 10pm, a retail union has warned.
Usdaw said stores remaining open until later in England were likely to become “very busy” with people buying alcohol, “triggering” antisocial behaviour.
Early pub closing was brought in last week in an effort to curb increasing rates of coronavirus.
The government says the measure has already worked in other countries.
Under the restrictions, which also apply in Scotland, pubs, bars and restaurants must shut no later than 10pm, but shops can continue selling alcohol until later.
On Monday, Greater Manchester’s Labour mayor Andy Burnham said supermarkets, convenience stores and off-licences were now “packed out to the rafters” after closing time.
Usdaw general secretary Paddy Lillis told the BBC the situation had left him “deeply concerned” for staff.
He added: “Sale of alcohol has always been a major flashpoint for violence, threats and abuse against shop workers, whether it’s age-identification or refusing a sale to someone who is already drunk, which are both legal requirements.
“Additional problems arise when licensing laws are not the same as shop opening hours or off-sales licensing hours are longer than on-sales.”
In Wales, under current rules, pubs must stop serving by 10pm and close 20 minutes after that. Shops also have to stop selling alcohol by 10pm.
Mr Lillis urged the government and councils in England to “ensure that when they bring in new rules they consider the impact on retail and the staff”.
“Stores in town and city centres are particularly at risk of becoming very busy late at night and that could make it more difficult for our members to enforce social distancing, which is essential for keeping staff and customers safe,” he said.
Restricting coronavirus transmission would “not be achieved by filling shops with late-night revellers”, Mr Lillis added.
In the House of Commons on Monday, Labour’s shadow health secretary Jonathan Ashworth said people were “piling out” of pubs at 10pm and questioned whether the deadline would help contain the spread of coronavirus.
Health Secretary Matt Hancock replied: “We always look at the effects of these policies. We’ve got to take everything into the round, including the level of social distancing that might have been going on were that [congregating] to continue all through the night.”
He added that “one of the reasons that we brought in this policy is because we’ve seen it work in other countries”.
Last week, Prime Minister Boris Johnson said: “What we’ve seen from the evidence is that the spread of the disease does tend to happen later at night after more alcohol has been consumed.”
For pubs in Northern Ireland, closing time remains at 11.30pm, although First Minister Arlene Foster said last week that no decision had been reached on imposing extra restrictions.
The UK government has been asked for a response to Mr Lillis’s remarks.