The owner of Heathrow airport says Britain must expand its airport capacity or lose out to rivals, as it announced that a record 70 million passengers used the London air hub in 2012.
Including interest payments on debt and one-off items, Heathrow reported a net loss of STG40.9 billion ($A62 billion) in 2012, compared with a loss of STG191.5 million a year earlier.
The airport saw an eight per cent rise in revenue to STG2.46 billion for the year of the London Olympics, and an underlying profit of STG46.4 million.
There were 471,341 flights to and from Heathrow in 2012, just below its absolute capacity of 480,000.
Owner Heathrow Ltd - formerly BAA - said "unlike its rivals in France, Germany, the Netherlands and Dubai, Heathrow is full and its capacity constraints prevent any meaningful increase in the numbers of flights and routes".
"This means the country's ability to trade with emerging economies is constrained, with potential long-term consequences for UK trade, jobs and economic growth," it said.
Heathrow's owners hope to build a third runway, but the idea has been stalled by strong opposition. The British government has ordered a review of Britain's airport capacity, but it is not due to report until 2015.