The timetable for the redevelopment of Heathrow was thrown into doubt yesterday after British Airways and BAA announced that BA’s planned move of its long-haul flights from Terminal 4 (T4) to Terminal 5 (T5) was being put back from April 30 to June.

The delay will have an impact on the entire airport because it will affect BAA’s refurbishment of T4, the company’s work on other Heathrow terminals and the schedule for other airlines to move into T4. After BA’s move to T5, a three-year renovation of other terminals was due to start, which would see other airlines move into the vacant space in T4.

The news came amid reports that Tessa Jowell, the Minister for London, said that BAA, the airports operator, should take financial responsibility for the economic cost of the T5 debacle.

The decision to delay the move will have a knock-on impact on 50 airlines, some of which have threatened to sue BAA for compensation.

Bmi, one of the affected carriers in the Star Alliance of airlines, reacted with fury to the delay, saying it was “outrageous and inconsiderate” and that the UK “was once again a laughing stock”. Nigel Turner, bmi chief executive, said: “BA through their mismanagement of the move to Terminal 5 will materially disadvantage all other airlines at Heathrow while BAA, through their perverse regulatory system, will benefit financially.”

Mr Turner said that he believed the Competition Commission and the Civil Aviation Authority would be interested in this latest development. “It is another example of how BAA is only interested in serving its principal customer,” he said.

BA and BAA said yesterday that the BA transfer from T4 was being postponed to iron out problems and give BA staff time to familiarise themselves with the new terminal.

Half of BA’s Heathrow staff are yet to work in Terminal 5. In the original April 30 plan, BA would have moved all its long-haul flights – 60 departures and 60 arrivals a day – to T5, leaving just its services to Bangkok, Singapore and Sydney in T4.

When the long-haul flights transfer, about 80,000 flyers will be using the new terminal. Willie Walsh, BA’s chief executive, said: “June 5 is the earliest possible date that we can transfer the long-haul flights but we will be sitting down with BAA in the next few days to see exactly how that will be phased.”

He did not deny that it might take all summer to phase in the flights. BA would identify any additional costs that this decision would incur and make them public as soon as possible, he added. Costs identified up to March 30 are £16 million, much less than had been speculated.

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