Heathrow owner BAA will be asked to sell one of its London airports after competition probe

Regulators are expected to demand the break-up of Britain's biggest airport operator BAA this week in a move which could end passenger chaos at Heathrow.

A 16-month probe into the dominance of the Spanish-owned company is expected to recommend the sell-off of at least one of its airports, which also include Gatwick, Stansted, Southampton, Glasgow, Edinburgh and Aberdeen.

Almost two-thirds of all UK passengers pass through airports owned by BAA and it controls 90 per cent of air passenger traffic in the London area.

BAA was at the centre of one of the industry's biggest debacles in March, when baggage-handling systems at Heathrow's Terminal 5 failed.

The group's owner, Ferrovial, was criticised for taking on too much debt when it bought BAA for £10.1billion in 2006.

Many experts believe this burden restricts its scope to invest.

Passenger groups believe queues and poor service experienced at crowded terminals are because BAA is a monopoly. They claim the company has no incentive to invest in improved facilities.

BAA was at the centre of the industry's biggest debacle this year when baggage handling systems at Heathrow's Terminal 5 failed

Airlines such as BMI and Ryanair supported the findings of an interim report in April, by the Competition Commission, which suggested that BAA's dominance restricted competition.

The latest report could be issued as early as Wednesday.

The Commission could order BAA to sell a named airport. More likely it will give it an option to sell Stansted as well.

There is also suspicion among analysts that BAA may be ordered to break up airports so individual terminals would be owned by separate companies.

None of its airports has been put up for sale but BAA chairman Sir Nigel Rudd said he had received expressions of interest.