Plane turned round because of ‘suspicious activity’

A US Airways flight to Florida was turned around because some passengers were engaged in ‘‘suspicious activity,’’ the FBI has said today.

The individuals were taken off the plane without incident yesterday and are being questioned by the FBI, spokeswoman Linda Vizi said. The suspicious activity was not specified.

Federal authorities decided to make USAirways Flight 335 return to Philadelphia, she said. The plane was headed to Orlando and carried 134 passengers.

The plane returned less than an hour after take-off. It was taken to an old terminal that is far from the main terminals at Philadelphia International Airport.

Bomb-sniffing dogs found no explosives, Vizi said.

‘‘From an abundance of caution since September 11, we want to make sure that everyone gets to their destination safely,’’ Vizi said.