Flight delayed by bomb threat –

State and federal law enforcement officers are investigating a bomb threat on an American Airlines flight that had stopped at Logan International Airport and was bound for Miami yesterday afternoon – the second such hoax in a month.

A flight attendant conducting a preflight inspection on the plane, a Boeing 757, found a note in the lavatory referring to a “Bomb on Board’’ and “Boston-Miami,’’ said Phil Orlandella, a spokesman for Logan Airport.

The plane, which arrived from Dallas at 1:45 p.m. and was set to leave for Miami less than an hour later, was held at the airport. Passengers who had already boarded were taken off, and the plane was diverted to the end of a runway. Investigators working with bomb-sniffing dogs inspected the plane’s cargo.