Retailers in England said on Tuesday they were again asking shoppers to wear masks but said they could not be expected to enforce the new law, fearing abuse of their staff.
From Tuesday face coverings became compulsory again in shops and on public transport in England in a bid to curb the spread of the new Omicron coronavirus variant.
Face coverings were already still mandatory in the devolved nations of Scotland, Wales and Northern Ireland.
English retailers said they supported the new measures as the safety of customers and staff was paramount but said it was not their job to enforce them.
Industry lobby group the British Retail Consortium said enforcement of face coverings must remain the duty of the authorities, a stance echoed by retailers.
"What I won't be doing is asking my store colleagues to police those who refuse to adhere to the rules. They're already working under significant pressure, especially as we hit the busiest trading month of the year," Richard Walker, managing director of the Iceland supermarket chain told BBC radio.
"The wearing of masks can be very divisive and I won't be putting my staff at risk of confrontation or abuse," he said.
Walker said if the government wants full compliance "then they must step in to help businesses like us and police the wearing of masks."
Tesco and Sainsbury's, Britain's two biggest supermarket groups, similarly said they were asking customers to wear masks, utilising new signs and posters.
Junior health minister Gillian Keegan said the government was relying on the "good sense of the British people" but noted the police could enforce with fines.
"We police by consent, we haven't been completely draconian as some other countries have," she told BBC radio.