Ferrovial already has interests in Bristol and Belfast airports

According to the Sunday Times newspaper, fund manager Scottish Widows said the firm would have trouble fending off a bid at that price.

BAA's stock has soared following the Spanish suitor's Ferrovial's revelation last week that it was mulling a bid.

The UK firm said it strongly advised shareholders not to take any action.

But Robert Waugh, head of UK equities at Scottish Widows, which holds a 3.1% stake in the bid target, told the Sunday Times: "Shareholders want something beginning with a nine."

"The company would struggle to defend the bid at this level."

'Unhealthy domination'

A �9.5bn offer - a 900 pence a share bid - would represent a 15% premium on the current BAA share price of 779p, on top of last week's 20% rally in its share price following Wednesday's announcement from Ferrovial.

Ferrovial's interest has attracted support from budget airline Ryanair's chief executive Michael O'Leary, who has long campaigned for the break-up of BAA, according to a report in the Sunday Express.

BAA operates most of the UK's major airports including Heathrow, Stansted and Gatwick.

In addition to its UK operations, BAA has a stake in 13 overseas airports, including operations in the US, Australia, Italy and Hungary.

It is the largest airport operator in Europe.

Ferrovial, meanwhile, already owns 50% of Bristol airport and has complete ownership of Belfast City airport.

A new owner for BAA would benefit airlines and passengers if it ended BAA's "unhealthy domination" over airports in the South-East, Mr O'Leary said.

"Putting all of the London airports together in one monopoly leads to high charges and the construction of marble palaces," he told the newspaper.

However, the Spanish company would not be able to alter charges directly as these are regulated by the Civil Aviation Authority.