A German furniture store chain has apologised for selling coffee mugs featuring faint portraits of Adolf Hitler it had mistakenly ordered from a Chinese supplier, a news report said on Thursday.

The vintage-style ceramic cups feature a faint image of a Nazi-era postage stamp that shows a black-and-white profile of Hitler, postmarked with a swastika stamp, all obscured by other design elements including a rose and cursive script.

The Zurbrüggen furniture chain had ordered 5,000 of the mugs and sold at least 175 when the mistake was noticed, reported the Neue Westfälische Zeitung in North Rhine-Westphalia.

The owner blamed the "terrible" mistake on "a stupid chain of unfortunate circumstances". "No one noticed the problem during unpacking," the store owner told the newspaper, adding that every customer who had bought a mug would get a €20 gift voucher.