It was noon. Time for lunch. And Fawn Hall was hungry.

So as she rode an escalator to board the Red Line at the Metro Center station in downtown Washington yesterday, Hall grabbed a banana from her purse, peeled it and, while waiting for the subway, began to eat. It was not a neat idea.

Such conduct on Metro platforms violates transit authority rules. Hall, who gained fame in the Iran-contra hearings as Lt. Col. Oliver North's secretary, was suddenly confronted by a Metro transit officer who issued her a $10 citation for eating the banana.

"Transit police asked her to quit, and she just kept eating it," said Metro spokesman Al Long.

Long said the ban on eating appears trivial, but he emphasized that the cleanliness of Metro transportation would deteriorate rapidly if the rule were not enforced.

But Hall angrily disputed the police explanation of the incident and said she would contest the ticket. She said she did not know eating was prohibited on a Metro platform, and disposed of the banana upon the officer's request.

"I was standing six inches from a garbage can, with most of the banana in my right hand, and a small piece in my left hand," Hall said. "The policeman came up to me yelling, 'Do you know that's unlawful?' I said I didn't, and threw what was in my right hand away."

But she had a few bits of banana in her left hand, which she slipped into her mouth.

Hall said the officer then said, "I told you eating the banana was a criminal offense." For the next 40 minutes the officer filled out the citation as a small crowd watched.

"I was in total amazement," Hall said.

She declined to repeat all that she told the officer, but said when he finally finished writing the ticket, she walked away and said, "I hope this has been the highlight of your day."