Sir Richard Branson has provoked outrage by telling Virgin Atlantic staff who are threatening to go on strike that they should “consider working elsewhere”.

The entrepreneur, estimated to have amassed a £3.1 billion fortune, sent a letter to 4,800 cabin crew, informing them he would not be meeting pay demands.

Union members have voted to stage two 48-hour strikes on January 9 and 10 and January 16 and 17.

In the letter Sir Richard states he has “drawn a line in the sand” in the dispute with staff belonging to the Unite union, which is currently embroiled in separate negotiation with BAA, the airport operator.

“To go further would result in unacceptable risks and would set a dangerous precedent to the company as a whole", he writes.

"It would be irresponsible of our management and they, rightly, are not going to take that risk.”

In an acknowledgment that other airlines offer more pay, he adds: “For some of you, more pay than Virgin Atlantic can afford may be critical to your lifestyle and if that is the case you should consider working elsewhere.”

In the letter, Sir Richard argues that staff using British Airway wages as a benchmark are being unrealistic. "It's like comparing chalk with cheese".

Virgin Atlantic does not have the benefit of a history of state support and priority landing slots, he writes. The carrier says it has offered staff 8.3 per cent on basic pay over two years, with a 4.8 per cent increase in the first year.

Paul Charles, Virgin Atlantic's director of communications, said: "We have been inundated with phone calls from staff who aren't on, saying 'we want to come into work to keep the airline flying'".

He added that nine-tenths of Virgin's flights will be unaffected over the strike period and that only 40 per cent of its workforce are Unite members.

The dispute comes as BAA management are locked in talks with union representatives in an attempt to prevent a series of walk-outs beginning on January 7.

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