Airport operator BAA has called time on its efforts to keep hold of Stansted and will sell the airport as ordered by the Competition Commission.

BAA has repeatedly challenged a Competition Commission ruling in 2009 that it sell Stansted along with Gatwick and one of its major Scottish airports, but has now accepted its legal options are exhausted.

The UK Court of Appeal recently upheld the Commission’s divestment ruling and BAA said today it had decided not to appeal.

Ryanair is considering whether to join a consortium bid for the airport. The carrier’s deputy chief executive Howard Millar revealed last month Ryanair had been approached by potential buyers with a view to joining a bid.

A Ryanair spokesman said the carrier would also be willing to guarantee its commitment to Stansted long term without taking a stake.

In a statement, BAA said: “Having carefully considered the Court of Appeal’s ruling, BAA has decided not to appeal to the Supreme Court and is now proceeding with the sale of Stansted Airport.”

However, it said: “We still believe the Competition Commission ruling fails to recognise that Stansted and Heathrow serve different markets.”

Stansted is London’s third-busiest airport and the UK’s fourth-busiest, but has seen traffic fall consistently through the economic downturn. It is largely a base for no-frills carriers such as Ryanair.

BAA reported the airport made an operating profit of £86.6 million in 2011.

The sale will leave BAA with four airports – Heathrow, Glasgow, Aberdeen and Southampton – after it was also forced to sell Gatwick and Edinburgh.

However, there was good news for BAA on Friday when the Qatar Investment Authority agreed to buy a 20% stake in the operator for £900 million.

The deal suggests confidence at the Qatari sovereign wealth fund that a third runway will be built at Heathrow.