File photo shows an aircraft lands at Heathrow Airport near London, Britain, December 11, 2015. [Photo/Agencies]

LONDON - The Scottish government announced Monday its support for plans to build a third runway at London's Heathrow Airport.

The endorsement comes as rival airports Heathrow and Gatwick eagerly await a decision expected within days about expanded air travel capacity in the skies above London.

The decision is likely to be one of the most controversial to be taken by the government this century, with strong opposition from people living beneath flight paths serving both airports.

May told the Conservative Conference in Birmingham last week that a decision would be made soon on whether to allow expansion at either Heathrow or Gatwick, or opt for another solution to create extra capacity in what is one of the world's busiest aviation hotspots.

The Scottish government in a statement said its support for Heathrow came after securing key commitments for Scotland from Britain's biggest airport.

"The expansion plans offer the greatest strategic and economic benefits to Scotland, creating thousands of jobs and providing a significant boost to the country's connectivity," said a statement issued Monday in Edinburgh.

The statement added that Heathrow's commitments include the creation of up to 16,000 new jobs across Scotland from the new capacity.

Heathrow will also work with the Scottish government to investigate Glasgow Prestwick Airport as a potential site for a logistics hub to support the building of the third runway.

There will also be 200 million pounds (248 million US dollars) worth of construction-related spend in Scotland during planning and construction and a 10 million pound route development fund to help support new domestic routes.

From January 2017, there will be a reduction of 10 pounds per passenger on landing charges paid by airlines operating services from Heathrow to Scotland, benefiting existing services from Aberdeen, Edinburgh, Glasgow and Inverness and incentivize the introduction of new services.

The commitments from Heathrow have been agreed in a memorandum of understanding signed Monday with the Scottish government.

Heathrow CEO John Holland-Kaye said: "An expanded Heathrow would create up to 16,000 jobs in Scotland. It would facilitate more airlines flying routes to Scottish airports, meaning more flights, more competition and choice for families and businesses across the nation."

The Airports Commission, which carried out a detailed study of future capacity in the London area, has recommended a third runway at Heathrow.

Heathrow says a three-runway airport will provide up to 740,000 flights a year, enough for Heathrow to compete on an equal footing with Paris, Frankfurt and Amsterdam. It also provides sufficient hub-airport capacity until at least 2040, they add.

Member of Parliament (MP) Louise Ellman, chair of the House of Commons Transport Committee, has also backed expansion of Heathrow.

The London-based Independent newspaper reported Sunday that bosses at London Gatwick aim to build a second runway, even if the government says expanded capacity will be at Heathrow.

Transport Secretary Chris Grayling is expected to announce a decision by Oct 18 at the latest.