Investigators found no proof of a bomb aboard a Thai Airways flight on Tuesday after a written danger was exposed in a lavatory shortly before its arrival in Los Angeles, officials said.

After landing safely, the Airbus A340-500 taxied to a remote area of the Los Angeles International Airport where official interviewed passengers and crew members, screened luggage and searched the plane.

"No proof has been found to propose a credible threat to the aircraft," FBI spokeswoman Laura Eimiller said.

The FBI is now investigating to decide who was responsible for creation the threat among the 171 passengers and 18 crew members on the Thai Airways International Flight 794 from Bangkok to Los Angeles, she said.

Eimiller could not verify reports that the threat was scrawled on a lavatory mirror.

Los Angeles airport official were notified of the threat around 90 minutes before the flight's scheduled arrival on Tuesday night.

It was not immediately recognized if passengers were conscious of the bomb threat during the flight.

Thai Airways said in a statement in Bangkok that airline officials were waiting for the plane to be released for its go back to Bangkok.