UK airports operator BAA is "dismayed" at the Competition Commission's confirmation that it must sell London Stansted and either Glasgow or Edinburgh airport, and is considering a judicial review of the decision.
BAA said the Competition Commission's ruling "has not recognised that the world and BAA have changed", and could cause damage to the company.
"A new government has changed aviation policy to rule out any new runway capacity in the South East and BAA has sold Gatwick Airport," said the airports operator.
"Both are significant changes to the airport market. Further, the airports in question face increased competition from non-BAA airports, particularly those in Europe, for the business of low-cost carriers who now take a pan-European view of the market."
The Competition Commission said in its decision that it accepted the switch in government policy was a significant change of circumstance, but it added that this "does not remove" the need for competition between airports in the south-east UK.
BAA said that "being forced to sell airports in a difficult market could destroy shareholder value", and added: ""We have a responsibility to protect our shareholders' investment and we will now consider a judicial review of the Competition Commission's decision."