BAA, Britain’s biggest airport company, signalled yesterday that a fourth runway and a seventh terminal could be needed eventually at Heathrow.

The Spanish-owned company is to open a fifth terminal at the West London airport in March and is planning to build a third runway and sixth terminal by 2020. It had previously indicated that this would be the limit of the airport’s expansion.

However, Stephen Nelson, BAA’s chief executive, refused yesterday to rule out further growth, saying that he did not want to make promises that the company might have to break.

Two possible locations for a fourth runway would be north of the airport alongside the M4 or south of the existing runways on land that is occupied currently by the villages of Bedfont and Stanwell. Both options would require the demolition of thousands of homes.

Appearing before the London Assembly, Mr Nelson was asked whether he was saying that there could be a fourth runway and seventh terminal. He replied: “It would be inappropriate for me to speculate on whether there would be a further case for expansion beyond 2030.” He said he did not want to give “hostages to fortune” by saying that the third runway would be the last big expansion.

Mr Nelson admitted that, 12 years ago BAA had given public assurances that proved to be false, saying that a third runway would not be needed.

In 1995 BAA stated in its official newsletter: “BAA has said repeatedly that Terminal 5 will not lead to a third runway. BAA has said repeatedly THERE WILL NOT BE A THIRD RUNWAY. And BAA has been proved right. The Secretary of State has accepted the BAA view. The issue has been settled; people’s concerns have been met. What now of those who claimed BAA was not telling the truth?”

In 2001 BAA and the Government accepted the recommendation of the planning inspector who approved Terminal 5 that the number of flights at Heathrow should be capped at 480,000. However, despite those BAA assurances in 1995, ministers now support a third runway and a plan was published in November that would increase the capacity to 702,000 flights.

The third runway. although shorter than the other two, is to be built on land currently occupied by the villages of Sipson and Harmondsworth.

Current growth trends suggest that the third runway will be full long before 2030 and Heathrow will once again face losing market share to airports on the Continent. Schiphol, near Amsterdam, has five runways and Paris Charles de Gaulle has four.

John Stewart, chairman of the Heathrow Association for the Control of Aircraft Noise, said: “After making so many false promises in the past, BAA has decided to be honest about the fact that it is keeping its options open for further expansion.

“But this means thousands more homes will be blighted by uncertainty. We fear that they will first lengthen the third runway and then build a fourth. The time has come to say enough is enough.”

A spokesman for the Department for Transport (DfT) declined to say whether the Government would support expansion beyond the third runway. Mike Tuffrey, the leader of the Lib Dems on the London Assembly, said that BAA and the DfT had “broken a catalogue of promises”.

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