BAA, the airport owner, is struggling to sell a portfolio of warehouses and offices around Heathrow and Gatwick and is under pressure to cut the £1 billion price tag by at least £100 million.

Ferrovial, the Spanish owner of BAA, has been trying to sell the property for more than a year, as it tries to reduce and refinance £8 billion of debt that it took on to fund its share of the purchase of BAA.

Airport Development and Investment, in which Ferrovial has a 61 per cent stake, bought BAA for £16.3 billion. However, the credit crunch has made debt refinancing more complicated and since the beginning of the year some of Ferrovial’s borrowings – £4.7 billion worth of bonds – have been attracting higher rates of interest.

Ferrovial is thought to be working on transferring those bonds into a new securitised vehicle, but it could face opposition from bondholders, thought to include Standard Life, Legal & General, Norwich Union, Scotttish Equitable, Axa and Clerical Medical.

BAA had hoped to sell its half-share in its £1 billion Airport Property Partnership by late autumn to help to ease its debt burden. Morley, BAA’s partner in the venture, decided that it would sell its half-share at the same time as BAA.

Sales talks between BAA, advised by bankers at Morgan Stanley, and the final-round bidders – Brixton, the industrial developer and Prologis, an American developer - fell apart late last year, with BAA refusing to budge on price. It is understood that the buyers wanted the price to be cut by 20 per cent.

The portfolio was valued last June at £1 billion, including about £600 million of debt. Two quarterly valuations since have failed to change the value put on the assets, despite the affects of the credit crunch and as fears of oversupply hit demand. The next quarterly valuation is due in March and property insiders expect the assets, including the BA World Cargo Centre at Heathrow, to be marked down by more than 10 per cent.

Meanwhile, BAA is understood to have hired investment bankers at Macquarie, the Australian bank, to explore raising a £1 billion loan secured against its regional airports – Southampton, Glasgow, Edinburgh and Aberdeen.

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