Either Edinburgh or Glasgow Airport is set to be sold after the UK competition watchdog ruled their joint ownership by BAA was harming passenger interests.

It is hoped that a sell-off would create greater competition between the two airports, leading to lower fees for airlines and cheaper ticket prices, as well as a push for greater investment in long-haul facilities at Edinburgh.

Glasgow Airport is currently better equipped to accommodate larger aircraft, but it is thought this would change if the airports were in direct competition.

BAA is expanding Edinburgh to handle bigger aircraft but experts claim this process would be accelerated after a sell-off.

However, council chiefs today warned any sale would risk the city's long-term economic future.

Rick Green, executive officer of Edinburgh-based airline flyglobespan welcomed the Competition Commission's findings.

He said: "If new owners were to come onboard, or BAA were to sell Glasgow, we would expect that there would be substantial investment in Edinburgh in order to compete effectively with Glasgow, especially on long-haul routes.

"We will be looking to plan which routes to operate the Boeing Dreamliner aircraft we have on order.

A key factor when deciding whether we will fly from Glasgow or Edinburgh will be the services available for these long-haul aircraft."

BAA has argued that there is limited scope for competition between Edinburgh and Glasgow because they serve different markets, but the Competition Commission found that 22 per cent of passengers at Edinburgh were from Glasgow's catchment areas.

John Strickland, of JLS Consulting, an independent air transport consultancy, said: "There are differences in the airports' infrastructure and this is likely to change if they were in competition.

"There are issues about the number of long-haul, direct flights that go into Edinburgh and there has been criticism in the past that BAA has been slow to invest in Edinburgh in this regard."

Councillor Tom Buchanan, the city's economic leader, said: "Any suggestion that this airport may be sold could seriously put at risk the city's economic future.

"We could not welcome anything which might risk the competitive position of the city."

BAA Edinburgh managing director Gordon Dewar said he believed the firm's stewardship of Aberdeen, Edinburgh and Glasgow airports had served Scotland well.