Backers of a cut-price scheme to expand Heathrow have repeated a call for an urgent review into plans for a third runway.

Heathrow Hub, promoter of an alternative extended runway, has written to the aviation regulator with its demand.

The board of the Civil Aviation Authority is reportedly meeting today (Wednesday) to consider a request from Heathrow for £3.3 billion of pre-application spending in preparation for the third runway.

Heathrow Hub wants long-time expansion opponent Boris Johnson to intervene, having previously written to transport secretary Grant Shapps calling for a review.

Heathrow Hub is also awaiting a judgement from the Court of Appeal on the government’s decision to support the third runway plan.

Heathrow aims to build a third runway by 2026 which would see annual passengers numbers rise from 80 million to 130 million with 740,000 flights from 473,000 in 2016. Overall expansion of the airport would be competed by 2050.

Heathrow Hub estimates the total cost of the third runway could be as much as £61 billion by the time it is completed although the airport puts the figure at £14 billion.

Willie Walsh, chief executive of British Airways owner International Airlines Group, believes the total bill for expansion is already running at £32 billion when the costs of building an extra terminal and aircraft stands are included.

Heathrow Hub claims its phased plan ensures that no new capacity need be introduced until the government and regulators are satisfied that environmental limits can be met.

The first phase would deliver up to 70,000 additional flights at a cost of £4.7 billion with no impact on passenger fees.

Heathrow Hub director Jock Lowe said: “It is absurd that Heathrow Airport Ltd is considering spending £3 billion on pre-application costs when it has not said what the full cost will be, still has no final scheme design and cannot say how it will build its new runway over the M25, right next to the M4 junction, without years of traffic chaos.

“Boris Johnson should stop his ministers fighting for Heathrow’s third runway in the courts, initiate a proper review and switch the government’s support to our cheaper, quicker, greener and simpler scheme, which delivers additional capacity at a fraction of the cost and, critically, only once environmental targets have been met.”

A CAA spokesperson said: “Expansion at the airport should be delivered in a way that helps airlines keep prices down for passengers.

“It therefore needs to be affordable, as well as allow Heathrow Airport Limited to finance the necessary investment.

“We are working hard to make sure the regulatory framework addresses these challenges in a way that delivers new capacity but without any unnecessary increases in airport charges.”