BAA is likely to become the subject of a bidding war after it emerged that an investment bank could trump Spanish construction group Ferrovial's £8.75bn offer for the company.

Goldman Sachs is understood to be considering forming a consortium to bid for the firm. It will make a final decision once it has gauged investors' reactions to Ferrovial's offer.

The Spanish contractor made a formal bid for the airport group last Friday by going over the heads of BAA's management and appealing directly to shareholders.

Its offer of 810p per share, which values BAA at £8.75bn, was immediately rejected by the BAA board.

Analysts at investment bank JP Morgan believe that BAA could achieve a value of between 839p and 862p a share if it is sold in the next 12 months, valuing the company at between £9bn and £9.3bn.

BAA dismissed Ferrovial's offer, which followed an initial proposal at the same value in March, as "not beginning to reflect the true value" of its assets.

Commenting on the offer last Friday, Marcus Agius, BAA's chief executive, said:

"We have already made our position on this offer crystal clear."

We remain keen to engage in a dialogue with the BAA board

Rafael del Pino, chairman, Ferrovial

Rafael del Pino, Ferrovial's chairman, said the bid consortium, which has backing from Citigroup, Royal Bank of Scotland, Banco Santander, HSBC and Calyon, did not see the bid as hostile.

He added: "We remain keen to engage in a dialogue with the BAA board with a view to securing a recommendation for the consortium's offers."

BAA is also reported to be planning a special dividend for shareholders to encourage them not to sell out to Ferrovial.

A spokesperson for the group declined to comment on the reports, and said it was too early to outline BAA's defence to Ferrovial's offer.

Ferrovial is being advised by financial groups Macquarie and Citigroup.