Airport operator BAA posted a 15 percent rise in first-quarter profit as it squeezed more growth from its capacity-constrained London Heathrow hub.

BAA, which is part owned by Spanish infrastructure group Ferrovial, on Wednesday reported earnings before interest, tax, depreciation and amortisation of 231.2 million pounds in the three months to the end of March on sales 11.5 percent higher at 537 million pounds.

The company said 15.7 million passengers passed through Heathrow - Europe's busiest airport - during the period, up 4.4 percent on the same period last year.

Heathrow remains resilient in a challenging economic environment, BAA Chief Executive Colin Matthews said.

Whilst traditional markets like the U.S. continue to perform well, the UK's capacity constraints prevent Heathrow from adding new routes to the emerging economies which are so vital for trade and investment.

BAA said it had completed the transition to long-term capital markets financing platform and had raised 2.2 billion pounds in new financing since the start of 2012.

Traffic at BAA's London Stansted airport, however, fell 5.3 percent to 3.5 million passengers.

(Reporting by Rhys Jones; Editing by Adveith Nair)