Glasgow Airport was last night said to be on the brink of a sell-off. The Herald understands Spanish infrastructure giant Ferrovial is looking at plans to put the airport on the market this month.

Glasgow Airport was last night said to be on the brink of a sell-off.

The Herald understands Spanish infrastructure giant Ferrovial is looking at plans to put the airport on the market this month in a bid to avoid a full-scale break-up of the company being imposed by UK watchdogs.

Any sale would effectively smash Ferrovial's near monopoly in Scotland: the company's subsidiary BAA, the former British Airports Authority, owns Glasgow, Edinburgh and Aberdeen airports and controls more than three-quarters of the Scottish market.

Airlines argue competition between Glasgow and Edinburgh airports could bring down fares to and from central Scotland and have urged competition authorities to force BAA to sell one or the other.

Earlier this year, the Competition Commission warned that the BAA monopoly in both Scotland and the south-east of England may be hurting passengers.

Yesterday, media reports suggested that the commission was now sure BAA's control of seven British airports, including London's Gatwick, Stansted and Heathrow, was harmful to the market. That, the Financial Times said, made sell-offs more likely.

Unnamed legal sources have been cited saying the next round of findings would be an important step towards an order for BAA to sell an airport in Scotland and an airport in England. Officials from rival airport operators are said to be have been consulted by the commission on what wider ownership would do for the industry.

The commission, however, is not expected to make its full findings public until later this month. Insiders told The Herald that Ferrovial was eager to make its own calls on which airport to sell. Spanish managers, they said, visited Glasgow and Edinburgh earlier this summer to size the two airports up. Edinburgh is now the bigger of the two and is still growing, despite a downturn that has cut passenger numbers in Glasgow.

The west coast airport, sources said, faces more competition than Edinburgh, from low-cost rival Prestwick, and is now seen as the best sell.

Senior sources last night said they were braced for an announcement on Glasgow's sale. Charlie Gordon, a Glasgow Labour MSP, has been calling for BAA to be broken up in Scotland for years. Last night, he said: "I would love to see some divestment in Scotland." Mr Gordon, in his former job as leader of Glasgow City Council, a few years ago half-jokingly offered to buy back the council-built airport.

A spokesman for BAA last night said it would only make a statement after the commission made its announcement.