The Prime Minister said he had "an open mind" about all airport expansion proposals, even though the Coalition has previously ruled out building a third runway at Heathrow.
Although the proposal to build a completely new airport in the Thames estuary is being examined, David Cameron said there were still "a range of options and possibilities", reports the Daily Telegraph.
This raised speculation that an expansion of Heathrow could come back on to the table in the next parliament.
"I’m not blind to the need to increase airport capacity, particularly in the south-east," he said. ""We need to retain our status as a key global hub for air travel, not just a feeder route to bigger airports elsewhere, in Frankfurt, Amsterdam or Dubai.
"Yes, this will be controversial. We will need to take decisions for the long-term – and we will be bringing forward options in our aviation strategy which will include an examination of the pros and cons of a new airport in the Thames estuary."
"The aviation paper that we will be producing will look at a range of options and possibilities, scope the whole issue but also look at what the estuary options are – obviously there is more than one."
Mr Cameron set out his vision for a bigger airport serving London in a speech today at the Institution of Civil Engineers arguing that Britain needs better infrastructure.
"Our roads are congested. Our key hub airport is full. I can see the furious objections – the banner headlines – already. But rather than give in we should ask instead ‘What is it that people want for the future?" he added.