BAA, the airports operator, has started legal action against Ryanair after the budget carrier refused to pay higher landing fees.

Ryanair said in April that it would not accept a 7 per cent increase in landing charges at Stansted. The airline asserts that the charges that Stansted imposes on each of its passengers has doubled to £10 in the past two years.

Ryanair has continued to pay BAA the previous fee and has put the difference into an escrow account while it challenges the increase. The airline has appealed to the Competition Commission to block the rise, which was sanctioned by the Civil Aviation Authority (CAA). This year the CAA allowed BAA to put up its charges at Heathrow and Gatwick. Over the next five years the landing fee will increase by 86 per cent at Heathrow and by 49 per cent at Gatwick.

The commission is investigating the fees dispute as part of a wider inquiry into the possible break-up of BAA's monopoly control of airports in the South East.

A Ryanair spokesman said: “We are going to fight the action. We don't think the fees are warranted.”

BAA said in a statement: “It is inappropriate to make any comment at this stage.”

Airlines have been critical of the increases in landing fees but have had little choice but to accept them and pass them on to passengers. EasyJet is seeking a judicial review of the process in an attempt to overturn the Gatwick increase.

BAA has also faced difficulties with some of the institutions that own its massive debt burden. Bondholders owning £4.7 billion of the company's total debt of more than £10 billion met yesterday to agree refinancing terms. About 90 per cent of bondholders had accepted the terms before the meeting, but a hedge fund client of UBS has refused to back the deal. If this unnamed bondholder does not accept the terms, the refinancing could collapse. The refinancing package will reduce BAA's interest payments in return for the debt being securitised against income from its London airports.

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