BAA has stepped up its defence against an £8.75bn hostile takeover bid from Spanish contractor Ferrovial.

The airport operators' management posted a document to shareholders this week to convince them to reject the offer, saying it was best placed to grow the business. It argued that it was already the largest quoted airport operator and had recently improved facilities at its Heathrow, Gatwick and Stansted.

The company said that under current management its assets were forecast to grow 20% from £10bn to £12bn in the next two years and that it was planning to invest £9.5bn over the next 10 years.

In a statement to the stock exchange on Wednesday, Mike Clasper, BAA's chief executive, reiterated his opinion on the 810p a share offer: "My message to shareholders is: don't sell. It's not the right time. It's not the right price."

There was speculation this week that Macquarie, the Australian bank that is advising Ferrovial, is planning to help to fund the bid.