Marks & Spencer has apologised after a Muslim member of staff refused to serve a customer trying to buy alcohol.
The retailer said it usually tried to assign "suitable roles" to staff who could not handle certain items because of their religious beliefs.
It said this policy had not been followed in a case highlighted by the Telegraph over the weekend.
Consuming alcohol is forbidden in Islam, and some Muslims refuse to handle it at all.
An unnamed customer told the newspaper they had tried to buy a bottle of champagne from an M&S store in London, but the member of staff "was very apologetic but said she could not serve me" and asked the customer to use another till.
A spokesperson for M&S 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.
'Beyond common sense'
"As a secular business we have an inclusive policy that welcomes all religious beliefs, whether across our customer or employee base... We apologise that this policy was not followed in the case reported."
But Khola Hasan, an Islamic law consultant, told Radio 4's Today programme she thought the M&S employee's refusal to serve the customer was "ridiculous".
"I don't think the Islamic ruling is being so difficult that Muslims cannot cope in society," she said, adding that Muslims could in theory object on religious grounds to serving customers buying any kind of meat, or items like cake or chocolate that contain small amounts of alcohol.
Other retailers said they would work with their employees on a case-by-case basis, to let Muslims avoid handling alcohol or pork, and would allow similar exceptions for other religions.
Asda chief executive Andy Clarke told BBC Breakfast: "We don't have a policy. If a colleague raises an issue with us, of course we'll deal with them on an individual basis, but we don't have a policy."
But speaking to Radio 5 live's On The Money programme on Sunday, Andy Street, managing director of John Lewis, said the company did not have a similar policy, and questioned whether members of staff should have the right to refuse to serve customers.
"This is taking it one stage beyond common sense," he told the programme.
"We certainly have never had any issue with our teams... we've not even had to have a policy on this. I would hope [members of staff] would understand that in their job this was probably going to be required."