Marks & Spencer has apologised after a Muslim member of staff refused to sell a customer alcohol.
The retailer said that where employees have religious beliefs that restrict what foods or drinks they can handle, it tries to place them in a "suitable role".
An M&S spokeswoman said: "We regret that in the case highlighted we were not following our own internal policy."
The issue arose after an unnamed customer at a London store told the Telegraph they were "taken aback" when an "extremely apologetic" Muslim checkout worker asked for them to wait for another till to become available.
The customer told the newspaper: "I had one bottle of champagne, and the lady, who was wearing a headscarf, was very apologetic but said she could not serve me. She told me to wait until another member of staff was available.
"I was taken aback. I was a bit surprised. I've never come across that before."
Drinking alcohol is forbidden in Islam, and some Muslims refuse to handle it.
M&S said its policy applied to staff of other religions, not just Islam.
The spokeswoman said: "Where we have an employee whose religious beliefs restrict food or drink they can handle, we work closely with our members 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.
"This policy has been in place for many years, and when followed correctly, we do not believe that it should compromise our ability to offer the highest level of customer service.
"We apologise that this policy was not followed in the case reported."
The case highlighted differences among retailers on whether religious staff should have to carry out certain jobs, the Telegraph said.
Sainsbury's guidelines say that there is no reason why staff who don't drink alcohol or eat pork on religious grounds could not handle them, the newspaper said, while Tesco said it made "no sense" for staff who refuse to touch items for religious reasons to work on a till.
Muslims working at Asda would not work have to work on tills if they objected to handling alcohol and Morrisons would "respect and work around anyone's wishes not to handle specific products for religious or cultural reasons", the Telegraph said.