BAA, part of Spain’s Ferrovial group, said the deal would provide a long-term funding platform for investment in its seven British airports, which include Heathrow, Gatwick and Stansted.

Bidders are lining up in the expectation that the Competition Commission will this week call on BAA to sell one or more of its airports, with Gatwick the favourite to go.

Both Germany’s airports operator Fraport and the country’s construction group Hochtief declared their interest in any sale.

Some reports have put the value of Gatwick at around £3billion ($5.6billion), although Collins Stewart analyst Andrew Fitchie said he found that valuation “quite incredible”.

“This is out of line with the fund­amental economics facing the aviation industry,” he said.

Fraport was interested in principle  and was reviewing whether it should take a stake in a BAA airport, said a spokesman.

“If an airport in Britain is for sale we would take a look at it,” said a Hochtief spokeswoman.