Hong Kong authorities said Monday they had launched an investigation after an airbridge collapsed at the city's airport, ripping the door off a Cathay Pacific plane and injuring a technician.

The boarding bridge for a Cathay flight bound for Nagoya in Japan on Sunday evening suddenly collapsed after all of the 262 passengers had boarded the aircraft, according to the Hong Kong Airport Authority and Cathay.

The rear bridge then smashed into the head bridge, which was connected to the first class cabin, ripping a door off the A330 aircraft. A technician who was trapped in the falling bridge at the time was injured.

"No passengers or crew members were on the airbridge at the time. We are investigating the cause of the incident," a spokesman from the Hong Kong Airport Authority told AFP.

The use of all rear bridges has been suspended for inspection, the official said, adding that passengers however would continue to board aircraft via the head bridges that are normally used by first class travellers.

He said the technician's condition was stable.

A Cathay spokeswoman said its aircraft was "slightly damaged" but would not comment on whether the home carrier will seek compensation from the airport authorities.

All affected passengers had left Hong Kong by Monday morning on alternative flight arrangements, she added.