Building a third runway at Heathrow would be cheaper and better for the economy, a report published by the airport argued.

The document, titled Best Placed for Britain, estimated expansion could be completed by 2025 – nine years quicker than a hub airport in the Thames Estuary.

But the report said the airport may need a subsidy from the taxpayer to expand, but it would cost a lot less than building a new hub airport.

The report, which is part of the airport’s submission to the Davies Commission, said the airport was best placed for passengers, with 4m more people within an hour’s travel time.

Closure of Heathrow may be forced if a hub airport is built in the Thames Estuary or Stansted Airport gets the go ahead to expand, meaning 76,600 directly employed at Heathrow would lose their jobs, the report said.

London Mayor Boris Johnson said Heathrow could be redeveloped into a major development complex.

He said: “There’s one of two options. It could either be a smaller Heathrow or you could ultimately create a fantastic new opportunity area with thousands of new homes, a university town, high-tech industries – it’s in exactly the right place.”

He said he thought it was “100 per cent unlikely” a third runway would be built at the airport.

Bosses at Heathrow said the prospect of building a third runway was “50/50” because they must wait for Government go ahead.

Heathrow’s development director John Holland-Kaye said: “We have never been more than 50/50.

“The easy option is to do nothing but we are running out of time to do nothing. We can’t afford to do nothing because we are handing business over to our competitors.”

He said even the estimated 2025 completion date was not quick enough, but was the best option for the country.

The airport will submit its plan to the Davies Commission next month, hoping to be shortlisted for recommendations published in 2015.

Mr Holland-Kaye said: “We need to come up with the best plan for London, the south and the UK. The Davies Commission is a very good vehicle to do that.”

Colin Matthews, CEO of Heathrow, said: “Britain already has one of the world’s most successful international hub airports in Heathrow.

“Expanding Heathrow will put Britain ahead in the global race, connecting UK business to growth more quickly and at less cost to the taxpayer than any other option for new capacity.

“Heathrow is better located for passengers, business and jobs.

“Why build from scratch at a new hub when we can build on the strength that already exists around Heathrow today?”