Spanish construction group Ferrovial, owner of London's Heathrow airport, says its net profits have risen to 488.5 million euros ($A615.12 million) in the first nine months of 2012, fed by international markets.
"The company's main businesses outside Spain performed well and offset declines in the domestic market resulting from the economic situation," it said in a statement.
Its net profits, equivalent to $US633.2 million ($A615.68 million), were up by 1.4 per cent in January to September compared to the same period last year.
Earnings grew particularly strongly at its two main assets, Heathrow and Canadian toll road 407 ETR, it said.
Ferrovial had seen its net profits plunge by 41 per cent in 2011 after it sold part of its stake in British airports operator BAA, which controls the Heathrow hub.
In efforts to reduce the debt stemming from this purchase, in August Ferrovial said it would sell off a further 10-per cent stake in BAA to the investment fund Qatar Holding.
Ferrovial had in 2011 sold a 5.88 per cent stake in BAA to US investment fund Alinda. The latest sale is subject to approval by European competition authorities and is due to be completed this year.