Disabled passengers arriving at Heathrow Airport are being forced to wait up to two hours for assistance disembarking aircraft, the aviation regulator has said.

The west London hub is one of four airports where the service for wheelchair users and other disabled passengers was judged to be "poor" by the Civil Aviation Authority (CAA).

Manchester, East Midlands and Exeter were the other airports where attention to accessibility was found to be lacking.

A survey of almost 1,200 passengers who use Heathrow's assistance service found that 62 per cent rate it as "poor" or "very poor".

The CAA recorded instances of passengers not being met on board arriving aircraft and not being treated with "dignity and respect".

On some occasions passengers have been encouraged to make their own way through the airport because of a lack of staff or equipment.

CAA consumer enforcement manager James Fremantle said: "There have been a number of occasions where people have had to wait one to two hours on arrival at the airport.

"Our view is... disabled passengers shouldn't wait any longer than other passengers."

More than one million passengers requiring special assistance travel through Heathrow every year - more than any other European airport. Its assistance service is provided by US-based firm OmniServ.

All of the "poor" airports have pledged to make improvements and the CAA said it will closely monitor them to ensure improvements are made in the coming months.

The report found that six airports provide "very good" assistance support, while 20 were described as "good".

A Heathrow spokesperson said: “We are extremely disappointed with these findings. They are not acceptable and fall short of the experience Heathrow aims to provide its passengers.

"Addressing the issues raised in this report is a priority for us. We apologise to those who have been affected and are taking action, including the amendment and retendering of our contract with new and higher standards of service, to ensure passengers who require special assistance, receive the service they rightly deserve.”

A spokeswoman for OmniServ said the company is "investing significant sums in staff training" and will "continue evaluating our performance... to provide the best service to all of Heathrow's passengers".

More than three million journeys were made by passengers requesting extra help in the UK last year, up 66 per cent on the figure for 2010.