This incident came to light when an unnamed customer spoke to the Daily Telegraph, relating his ordeal at the store in London where he wanted to buy Champagne and was made to wait for long hours by a staff member till another staff was available.
"I was taken aback," the customer said. "I was a bit surprised. I've never come across that before," he further added.
Marks and Spencer official said, "We regret that in the case highlighted we were not following our own internal policy. As a secular business we have an inclusive policy that welcomes all religious beliefs whether across our customer or employee base."
Meanwhile, a "Boycott Mark and Spencer" page was started on Facebook said that the policy was an "affront to common sense".
"This is taking it one stage beyond common sense," managing director of M&S Andy Street said.