Proposals to build a replacement for Heathrow in the Thames estuary have taken significant steps forward with Boris Johnson, the mayor of London, preparing to appoint the civil engineer behind Hong Kong’s giant island airport to examine the viability of the project.

The move comes as senior MPs have set up a cross-party group to lobby the government to investigate the idea.

Douglas Oakervee, the engineer who also chairs the Crossrail project for an east-west rail link in London, will tomorrow discuss with Johnson’s officials the terms of his involvement in a feasibility study.

Oakervee was the lead engineer in the construction of the £12 billion Hong Kong international airport, which was opened on mainly reclaimed land in 1998. The Thames estuary idea being drawn up by Johnson’s officials is loosely based on Hong Kong.

Pressure to replace Heathrow is growing as the government prepares to announce its decision on whether to build a third runway at the airport in the face of mounting environmental protests and rebellion from some cabinet ministers and local Labour MPs.

Kit Malthouse, Johnson’s deputy mayor, said momentum was building behind the estuary project. “There is no question we can achieve this,” he said. “We have to rediscover our tradition of ambition in civil engineering. The irony is that British engineers have already done it in Hong Kong. We can bring their ambition to London if there is the political will.”

Bernard Jenkin, the Tory MP for North Essex, who is heading the new all-party group, said: “Privately, government ministers – including in the Department for Transport – view the proposal much more favourably than the official line.”

In a sign of growing cross-party support, Nick Raynsford, a Labour MP and former minister for London, will join Jenkin among the first members of the group, likely to be launched in the next 2-3 weeks with 20 members. “There are a lot of Labour MPs who are already extremely uncomfortable about the expansion of Heathrow,” he said.

“An airport to the east would, at a stroke, rebalance the economic geography of the capital. It would make a reality of the regeneration of the Thames Gateway, create jobs and attract industry to an area of deprivation.”

Despite Gordon Brown’s support for a third runway at Heathrow, concerns are growing. This week ministers will be sharply criticised for “burying” plans to levy a congestion charge on vehicles using roads around Heathrow, even if they did not enter the airport, to help pay for the expansion.

The idea was put forward as one option in a technical document sent out a year ago without fanfare by the government.

In a motion to be tabled tomorrow, three MPs with constituencies near Heathrow – Justine Greening, a Tory; Susan Kramer, a Liberal Democrat; and the Labour member Alan Keen – will accuse the government of trying to smuggle the plans out without properly consulting the public.

Geoff Hoon, the transport secretary, has said he believes there is a strong case for a change in takeoff and landing patterns at Heathrow that would condemn residents to 18-hour periods of uninterrupted noise. Currently, planes use one runway for taking off and one for landing, switching every few hours to give residents a break from the din.

Using mixed mode, in which both runways are used for both takeoffs and landings, would enable flight numbers to be expanded, but would give residents no respite.

Hoon said no decision had been taken but that an announcement would be made when the final decision on the third runway was made public.

“Mixed mode is perfectly normal,” he said. “It [Heathrow] is running very near its limits at 98.5%. That has significant implications, not least [that] if there is a problem at the airport, planes very quickly back up. There is an environmental cost to that. Mixed mode will relieve some of that pressure.”

Additional reporting: Jonathan Oliver

Times Recommends

• A vicar’s wife: ‘There is no one to fight for us’
• Every little helps at the supermarket
• Ugg or Fitflop? The battle of the boots