A plane made an emergency landing in Boston when its cabin filled with smoke mid-flight.

The Airbus A350 on flight CX811 was just 30 minutes into the journey to Hong Kong when thick smoke began filling the cockpit and cabin area shortly after midnight on January 20.

Footage shows visibility obscured as the white vapours filled the jet, which had taken off from Boston Logan International Airport in Massachusetts.

The twin-aisle aircraft had reached an altitude of 5,000ft before circling back towards the same runway it had just departed from. It flew in a holding pattern to dump fuel before making the emergency landing at 3:31 am local time.

Hong Kong flag carrier Cathay Pacific said in a statement the 'precautionary flight return' was executed 'in accordance with standard procedures'.

The airline added: 'Safety guides every decision we make. We sincerely apologize to the affected customers for the inconvenience.'

There were no injuries reported and the cause of the smoke was under investigation, officials said.

Passengers were put on a later long-haul flight to return to the former British Crown Colony, which was first acquired by Queen Victoria in 1842 but has been backsliding into authoritarianism since being returned to China.

Many Hong Kong residents have sought refuge in the United Kingdom and United States.