Marks & Spencer appeared to backtrack on Sunday night by issuing an apology after a Muslim member of staff refused to serve a customer trying to buy champagne.
Previously the supermarket said Muslim staff can refuse to serve customers who are trying to buy pork or alcohol.
But a spokesperson for M&S last night said: "Where we have an employee whose religious beliefs restrict food or drink they can handle, we work closely with our member of staff to place them in suitable role, such as in our clothing department or bakery in foods.
"As a secular business we have an inclusive policy that welcomes all religious beliefs, whether across our customer or employee base ... We apologize that this policy was not followed in the case reported."
The issue arose after an unnamed customer told the Telegraph they were "taken aback" when "I had one bottle of champagne, and the lady, who was wearing a headscarf, was very apologetic but said she could not serve me".
It has highlighted a split amongst the major supermarkets, between those who will and those who will not excuse staff from certain tasks for religious reasons.
Morrisons said it had a great deal of experience dealing with the issue because it is based in Bradford, where there is a large Muslim community.
It said it would "respect and work around anyone's wishes not to handle specific products for religious or cultural reasons".
Sainsbury's, meanwhile, has issued its official policy on the matter in the form of a pamphlet called "The Little Book of Faith". It said it had come up with the guidance following research conducted with religious groups, and had concluded that just because a person was not able to eat pork or drink alcohol didn't mean they should be allowed to avoid handling them altogether.
Asda and Tesco both said they were unlikely to employ a person on the tills who could not handle some goods - though the latter said they dealt with the issue on a case-by-case basis.
An M&S spokesperson had told the Telegraph: "We recognize that some of our employees practice religions that restrict the food or drink they can handle, or that mean they cannot work at certain times.
"M&S promotes an environment free from discrimination and so, where specific requests are made, we will always make reasonable adjustments to accommodate them, whilst ensuring high levels of customer service."
The policy appeared to anger the biologist and author of The God Delusion, Richard Dawkins, however. He wrote on Twitter: "So, can followers of the Flying Spaghetti Monster refuse to sell pasta? Could I refuse to sell baseball caps?
"These Marks & Spencer tweets may seem frivolous. But they are serious examples of the kind of RIDICULE religious discrimination deserves."
The outspoken former Apprentice candidate Katie Hopkins tweeted on the subject: "It is not a myth. M&S hoping to attract Saudi investment I wonder?"
Yet others supported the retailer, with Channel 4 journalist Fatima Manji writing: "Note how it says they accommodate all religious belief on case by case basis, but people fixated by the Muslim bit."