Miami - A Florida tour boat operator had his hand bitten off as he was feeding an alligator marshmallows to entertain passengers, officials said on Wednesday.

The boat was carrying six tourists late on Tuesday when the alligator leapt up and devoured the sweets along with the captain's hand, according to Jorge Pino, a spokesperson for the state Fish and Wildlife authority.

The alligator was tracked down and killed and the hand was extracted from its stomach, but doctors' efforts to re-attach it at a hospital in Tampa proved unsuccessful.

To add insult to injury, the boat captain finds himself facing the possibility of a $500 fine or six months in prison because feeding alligators is a second-degree misdemeanour in Florida.

The boat was operated by Doug's Everglades Tours, one of several companies that carry tourists up and down the state's popular, subtropical wetlands.

The incident occurred near Everglades City, 130km north-west of Miami. - AFP