A Norwegian flight en route from Stockholm to Nice on Thursday was forced to return to Stockholm following a "bomb threat."

The airline confirmed the incident in a statement on its website.

"Norwegian can confirm that a bomb threat has been made against flight DY4321 from Arlanda to Nice," the statement said.

"For safety reasons, the aircraft returned to Arlanda."

Stockholm police also released a statement, saying it had launched an investigation into the threat.

All 169 passengers and flight crew have now been evacuated, Swedish police said, adding the national bomb squad would shortly begin a search of the plane.