The US company which has tried to buy Manston airport three times this year has told a Government-appointed commission the site could ease capacity constraints in the South East.

RiverOak Investment Corp claims the recently-closed Thanet airfield is part of an immediate and long-term solution to dealing with growing air traffic set to come through the UK by 2020.

The claims are in response to the Airports Commission’s calls for evidence about how the Government can best use the UK’s existing airport capacity to deal with the problem.

RiverOak said that Manston was the sixth busiest air freight airport in the UK last year, with freight volumes greater than Luton, Belfast, Edinburgh and Birmingham.

The 30,000 tonnes of cargo handled is the equivalent to 300,000 passengers in terms of workload.

The Department of Transport forecasts that £42bn of air cargo will be lost to London airports because of capacity constraints by 2020 – with RiverOak claiming Manston can take up the slack.

The Connecticut-based consortium also said in its evidence that Stansted is the only other South East airport to take dedicated cargo, but that Stansted’s plans to expand its low cost passenger services will limit any expansion of its cargo operations for the remainder of the decade.

RiverOak has said it will financially support an attempt by Thanet District Council to buy the airport – which was closed in May – using a compulsory purchase order (CPO).

In its three attempts to buy the airport from owner Ann Gloag before its closure, it said it believed the site had a future as a dedicated cargo operation.

RiverOak spokesman Tony Freudmann said: “The research we commissioned for this response has confirmed what we already knew, namely that there is a strong demand for a range of air services at Manston and that Manston can play a key role in relieving some of the pressure on capacity at the airports surrounding London.

“Our proposal is that if the CPO is confirmed, Manston should be re-opened in 2015/16 as a Sky Port and Integrated Aviation Services Hub.

“The initial focus would be on re-establishing the airport’s cargo business, particularly in the perishables niche with business aviation, emergency service work and the flying school.

“This would be followed by facilities for aircraft maintenance and teardown, with passengers following in the summer of 2017.

“Manston would also be re-established as key diversion airport capable of providing emergency resilience in the wider South East airport system.”