The Spanish consortium bidding for British airports operator and Heathrow owner BAA has increased its offer for the company from £8.75 billion to £9.73 billion.
The increased offer of 900p a share was rejected by BAA, but it represents a premium of 41% to the average share price before bid speculation began in February and is 11% more than Ferrovial's previous offer.
Ferrovial signalled last week that it would not be deterred by a regulatory review into the airports sector by Britain's Office of Fair Trading (OFT).
BAA told shareholders in a defence document last week that it believed it was worth at least 940p a share - equivalent to £10 billion.
The OFT is considering whether to look into the UK airports market with a view to seeing if it works well for travellers. The review was welcomed by EasyJet and Ryanair as the low-cost airlines have previously lobbied for an investigation.
