McDonald’s has been forced to apologise to a US customer after she was served a chicken sandwich with a swastika drawn onto the bun with butter.

Charleigh Matice, from Carteret County in North Carolina, was visiting the drive-through at her local branch of the restaurant with her daughter and ordered a southern-style chicken sandwich.

When she opened it up to add mayonnaise she discovered the Nazi symbol etched into the underside of the top half of the bun.

The customer returned to complain to restaurant staff, at which point they offered to replace the meal. But Ms Matice told WCTI Channel 12 News she had lost her appetite at that point and demanded a refund.

“Is this a joke? Does somebody really think they're funny?” she said. “Many people died because of that symbol and it’s not something that should be taken lightly. It’s not something that should be thrown around.”

Ms Matice said she had found the swastika extremely offensive, particularly as her grandfather had fought in the Second World War.

McDonald’s has since admitted that the incident was “unacceptable” and said that the employee involved had been fired.

In a statement issued by the Morehead City branch owner Dulcy Purcell, the restaurant said: “We are very sorry for the service that our customers received, and to be clear we have terminated the employee who was involved.

“We do not tolerate that kind of behaviour at McDonald's, and it's not what we stand for personally as owners. It is about providing the best level of service and care to our customers, and anything less than that is unacceptable to us.”

Ms Matice said that while she felt the incident raised questions about the training McDonald’s staff received, it would not stop her from eating there again.