The City of London authority has announced a clampdown on dishonest operators who display false food hygiene ratings in their windows.
Spot checks saw trading standards officers visit 140 premises to find that 22 of them were displaying a food hygiene rating higher than what they had been awarded.
Angela Towers, head of the Food Standards Agency's food hygiene rating team, said: "People have a right to trust that the hygiene rating displayed in a restaurant's window is accurate and we are pleased that the City of London Corporation has taken action against a small minority of food businesses who have sought to mislead the public."
Jeremy Simons, chair of the City Corporation's port health and environmental services committee, said: "The rights of consumers to make informed choices about the food they eat is something we take very seriously.
"Where we have found restaurants being dishonest, we have acted quickly to rectify the situation.
"Food hygiene standards are very high in the City, with 96% of outlets having a rating of three or more. But we will continue to work with the other premises to ensure they understand the importance of upholding the best standards in their businesses."
Officers subsequently returned to the offending establishments and oversaw the removal of the false ratings, before sending a written warning.
It is not mandatory to display a food hygiene rating sticker.