San Francisco: The head of a San Francisco Bay Area commuter train system apologised to a black rider who was detained and cited by police for eating a breakfast sandwich on a train platform after an outcry from people who assailed enforcement of a no-food rule as racist.

A Bay Area Rapid Transit train in Oakland, California. Credit:AP

More than two dozen people staged an "eat-in" at a Bay Area Rapid Transit station over the weekend and others continue to protest the November 4 encounter, which ended with a 31-year-old man, who was headed to work, in handcuffs and unable to leave until he had told BART police his name.

BART officials said on Monday that an independent auditor is investigating. Eating is not allowed in paid portions of stations to maintain cleanliness, but it shouldn't be used to prevent people from getting to work on time, they said.

"We have to read each situation and allow people to get where they are going on time and safely," said Bob Powers, BART's general manager. "I'm disappointed how the situation unfolded."