AIRPORT bosses at Heathrow have vowed to launch up to 21 extra daily domestic flights by 2021 if ministers give the go ahead to expand the hub, with a direct flight for Dundee among the potential new routes being tabled.

The proposals were unveiled amid reports that a majority of Conservative MPs now back a third runway at Heathrow, paving the way for Prime Minister Theresa May to win a vote on the issue in parliament. A final decision is expected when the Cabinet aviation subcommittee, chaired by Mrs May, meets on either October 11 or 18.

Heathrow bosses said that, if their expansion plans are approved, they would begin growing the domestic route network from 2021 - four years before a new runway would open - by bringing forward £10 million in start-up capital to support extra UK regional flights.

In a statement they said the package was "a huge win for Scottish cities" with a possible new connection with Dundee and increased frequency for existing Scottish services to Glasgow, Edinburgh, Aberdeen and Inverness.

The average number of daily flights departing from Scottish airports to Heathrow has declined from 50 in 2005 to fewer than 30 today as slots have increasingly gone to more lucrative long-haul destinations, with the demise of Virgin's Little Red in 2014 also reducing the number of daily Scotland-Heathrow flights.

Heathrow management have also proposed extending the £10 discount on passenger charges, due to come into effect from January on all flights, until 2037 "as long as there is justification and it is deemed to be in the public interest".

They also reiterated their commitment to creating a supply chain hub in Scotland where hundreds of people would be employed to assemble the materials used to construct a third runway.

Amanda McMillan, managing director of Glasgow Airport, welcomed the proposals.

She added: “Our passenger statistics show that Heathrow remains the dominant airport for onward connectivity.

"It plays an important role in supporting the Scottish economy, so it is imperative that our links with the UK’s only hub are not only maintained but, where possible, enhanced."

As well as up to 21 extra domestic flights, Heathrow said it could also add 13 new daily services long-haul destinations currently not served by the airport including Quito in Ecuador, Wuhan in China, Goa, Katmandu, Kochi in India, and Kansai Airport, which serves Osaka in Japan.

Carol Benzie, managing director of Aberdeen International Airport, said: “Heathrow is the most popular route from Aberdeen International Airport and this is because of the onward connectivity it provides. Following the withdrawal of the Little Red service in September 2015, we went from having 11 flights per day to Heathrow to eight and we simply cannot allow our connectivity with the UK’s hub airport to wane any further."

The latest push to persuade ministers' to back a third runway comes after Foreign Secretary Boris Johnson said Heathrow expansion was a "fantasy" that should be sent "to the dustbin".

The former London mayor - a long-time opponent of Heathrow expansion - said the "massive costs and enormous risks" made the project undeliverable.

Ministers could also opt for a second runway at Gatwick or to extend one of Heathrow's existing runways.

However, Heathrow chief executive John Holland-Kaye said a third runway at Heathrow was “the only option that can help every nation and region of the UK realise the opportunities of Brexit".

He added: "The Prime Minister and the Government can now to make the right choice, and back Heathrow expansion."