Grupo Ferrovial, the Spanish construction, services and infrastructure group, said yesterday it was considering a cash offer for BAA, the UK airport operator that runs London's Heathrow and Gatwick airports.

Ferrovial said it had not yet approached BAA but was considering forming a consortium to make an offer.

That sent BAA shares soaring by 11 per cent to 752½p, giving the group a market capitalisation of £8.1 billion (€11.8 billion).

The Spanish group already has a presence in the UK airport sector - it jointly controls and operates Bristol airport in the west of England with Macquarie and also owns Belfast airport in Northern Ireland.

Last year it paid €646 million for Swissport International, the airport handling company previously owned by Swiss Air, which operates more than 180 locations worldwide.

Ferrovial declined yesterday to give more details on its plans for a BAA bid, citing Takeover Panel restrictions in the UK.

However, taking on BAA would be a far bigger proposition than anything Ferrovial has looked at before in the airports sector.

BAA's facilities include Heathrow, which remains Europe's busiest hub, as well as Gatwick and the fast-growing Stansted airport, north-east of London.

Since 1997, Ferrovial's strategy has been one of sectoral diversification and geographic expansion.

The Spanish construction services firm's net profits last year were €556.8 million, compared with BAA's pre-tax profits for 2005 of £733 million.

In Australia, the Spanish company has a 20 per cent stake in the consortium - which includes Macquarie - that runs the international airport in Sydney.

Ferrovial also has the concession on a regional airport in Antofagasta, which serves the copper belt in northern Chile.