A helicopter on an 'unauthorised' flight crashed into the roof of a hotel in Australia's northern tourist town of Cairns on Monday, killing the pilot and forcing the evacuation of hundreds of guests, authorities said.

Emergency crews were called at about 2 a.m. (1600 GMT on Sunday) after the twin-engine helicopter hit the hotel roof, causing a fire and triggering the evacuations, Queensland state police said in a statement.

Police said the helicopter had been taken from its hangar for an "unauthorised flight", but did not elaborate. The pilot, who has yet to be identified, was declared dead at the scene.

The crash took place at Hilton's Double Tree Hotel in Cairns, a gateway city on the route to the Great Barrier Reef, Australian media said.

Two hotel guests, a man in his 80s and a woman in her 70s, were discharged after being taken to hospital, state broadcaster ABC said, adding that two of the helicopter's rotor blades came off with one landing in the hotel pool.

The forensic crash unit will work with Australia's transport safety regulator to prepare an accident report, police said.

Helicopter owner Nautilus Aviation said it was co-operating with the police investigation.