BAA has begun lobbying for a full-length new runway at Heathrow ahead of the expected launch next month of a consultation document on expansion of the London airport.

The move represents a switch for BAA, which has in the past advocated only a short extra runway, suitable for the small aircraft used on short-haul flights.

A full-length strip – Heathrow’s existing runways are full-size at about 4,000 metres – would allow more flights by larger, long-haul aircraft.

BAA declined to comment, but industry sources confirmed the change in policy. “They are pushing hard on a full-length runway – which I find difficult to understand. I think it is because they think, possibly rightly, that getting any new runway at Heathrow is going to be a monumental battle, so they may as well go the whole way,” said one executive.

The government is expected to publish a consultation document on the expansion of Heathrow next month. This will cover proposals for more flights on the airport’s two present runways, and for a third runway.

Both plans are expected to be bitterly opposed by local residents and environmental groups. Heathrow was last month the scene of a “climate camp” at which green campaigners gathered to protest against aviation’s contribution to global warming.

The consultation is the result of a government white paper on the future of air transport issued four years ago. It said that while there was an economic case for expanding Heathrow, it could not proceed until local air-pollution issues were addressed. Stansted was chosen as the location for the southeast’s first new runway.

Meanwhile BAA has appointed Merrill Lynch to conduct a review of the future of World Duty Free, its airport retail business.

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