A UNITED Airlines flight bound for Los Angeles was forced to return to its origin of Honolulu after a possible threat was found on board.

The “potential security concern” was found in the plane’s restroom.

Flight tracking information on FlightAware shows that an hour-and-a-half into the flight, which left at 9:40 pm on May 20, UA1169 made a 180-degree turn back to the Daniel K. Inouye International Airport.

The airline confirmed that the security threat was found written on the lavatory mirror, local CW affiliate KTLA reported.

No further information was provided as to what the threat said.

The spokesperson confirmed that law enforcement searched the plane after it landed.

“We are rebooking customers on another flight to Los Angeles that departs later this evening,” the spokesperson told KTLA on Wednesday morning.  

The possible security threat came hours after a passenger was arrested on a Hawaiian Airlines flight departing from San Diego and heading to Honolulu.

Flight HA 15 was diverted off the tarmac as a passenger made a bomb threat.

The 283 passengers on board were forced to deplane around 10:30 am.

“During pushback from the gate, a guest was overheard making a threat to the safety of our aircraft,” a spokesperson for the Port of San Diego Harbor Police confirmed to FOX 5.

“As a precaution, the captain immediately taxied the Airbus A330 to a safe location on the airfield, where it was met with local and federal law enforcement and guests were safely deplaned.”

A passenger on board filmed armed cops on board as they searched the aircraft for explosives.

“Bomb threat was called on the plane,” the passenger captioned the video.

The flight was reportedly moved to a secure location and was checked by K-9 units.

After searching the plane, authorities discovered “nothing suspicious” on board, KTLA reported.