Birmingham Airport’s campaign to be named a national facility is to receive a major boost when Liberal Democrats urge the Government to block new runways at Heathrow – and expand regional hubs instead.

Delegates at the party conference in Brighton next month are likely to endorse a motion backed by Lib Dem MPs which highlights the potential for growth at Birmingham.

But the plea will put them at odds with some of their coalition partners, after a number of Conservative backbenchers backed new runways at Heathrow.

Transport Secretary Justine Greening, a Conservative, is working on an aviation strategy which has been repeatedly delayed. She has praised Birmingham Airport in recent months, but she is under pressure from some Tory colleagues and from London’s business community to allow new runways to go ahead at Heathrow, even though this was explicitly ruled out in the Conservative general election manifesto.

Birmingham Airport argues that a planned runway extension will allow it to serve 27 million passengers a year, up from nine million at the moment, and to provide long-distance flights to locations such as India and China. High speed rail will also make Birmingham as convenient as Heathrow, the airport says.

But it insists it needs formal government backing to allow it to expand, and is lobbying the Government to reject calls for a new runway at Heathrow.

The campaign is set for a boost when Lib Dems debate a motion proposed by MP Julian Huppert, Co-Chair of the party’s Parliamentary Committee on Transport, and backed by colleagues including Solihull MP Lorely Burt (Lib Dem Solihull).

The motion states: “Aviation policy has to date focused on London and the South-East; it is clear that that is where the greatest demand lies, but airports and foreign travel for business or leisure must be easily accessible for citizens living across the UK.

“With Birmingham looking to expand, Stansted only half full and Gatwick expanding into emerging markets, regional airports and other airports within London can meet demand for years to come.”

And it calls on the Government to reject calls for new runways at Heathrow, Gatwick or Stansted, as well as London Mayor Boris Johnson’s proposal for a new Thames Estuary airport.

As well as highlighting Birmingham, the motion calls specifically for better use of existing capacity at Gatwick Airport.

It also states that the UK will need a single hub airport in the long term, although this should not be Heathrow.

It calls on the Government to set up “an independent, evidence-based study to find a suitable location for a hub airport, or a suitable airport to expand into a hub.”

Ms Burt said: “It is really important that, before we start spending billions on Boris’ new airport or clogging up the area around Heathrow even more, we look at the capacity that already exists in our regional airports, and in particular at Birmingham.

“Birmingham could double its current passenger numbers without any need for a new runway.

“If we focus entirely on the south east, then other parts of the country are never going to reach their potential.”

Mr Huppert said: “Aviation policy has focused on London and the South East and it is clear that is where the greatest demand lies; but airports and foreign travel for business or leisure must be easily accessible for citizens living across the UK. “

A report by Tory backbenchers including Harriet Baldwin (Con, West Worcestershire) and Jesse Norman (Con, Herefordshire) called in July for not one but two new runways at Heathrow.

Published by the Free Enterprise Group, which includes a number of younger Conservative MPs, the study was called Seven Shots in the Arm of Britain.

It said: “The Government should grant planning permission for both a third and fourth runway at Heathrow.

“Britain’s hub airport Heathrow is currently at 99 per cent capacity, and London’s other airports are nearly as full. Demand is predicted to double over the next few decades.

“If new aviation capacity is not found, London’s position as a world business hub will be damaged. Heathrow is almost unique among major world airports in only having two runways, with no plans or further construction.”

Business leaders in the West Midlands including Jerry Blackett, chief executive of the Birmingham Chamber of Commerce Group, criticised the report at the time.