BAA has succeeded in its appeal against a order to sell off three of its UK airports, after a tribunal agreed that the Competition Commission (CC) had been influenced "apparent bias" in its original ruling.

In March, the commission ordered the airport operator to sell off Gatwick, Stansted and either Edinburgh or Glasgow in the interests of passengers and airlines, although the BAA appealed the decision on the grounds that the commission had not been impartial in its inquiry.

The Competition Appeals Tribunal (CAT) ruled "unanimously" in favour of BAA's claim that Professor Peter Moizer's inclusion as part of the inquiry team had led to "apparent bias" due to his role as an advisor to the Greater Manchester Pension Fund, linked to Manchester Airports Group (MAG) - a potential bidder for BAA assets.

According to the CAT judgement, a "fair-minded" obsever would see a "real possibility" of bias due to Moizer's involvement, with MAG wholly owned by the 10 local authorities of Greater Manchester, which governs the Greater Manchester Pension Fund.

Both sides will now be given more time to discuss whether BAA should be forced to sell Stansted and either Edinburgh or Glasgow, with the Spanish-owned operator having already offloaded Gatwick to Global Infrastructure Partners (GIP) in October irrespective of the CC ruling.

A BAA spokesperson said: "We are pleased that the Competition Appeal Tribunal upheld our appeal on the grounds of apparent bias. Further discussions should now take place with the Competition Commission, as the CAT suggests, to determine the appropriate response to this judgement."

However, BAA's second argument that the CC had not taken account of the recession in outlining the timescale for the sale of the airports was rejected by the tribunal.