The £8bn redevelopment, with 7,500 new homes, was approved by Kensington and Chelsea’s Planning Committee two weeks ago, with the Mayor currently residing over whether to accept or reject the proposals.
Labour London Assembly Planning member Nicky Gavron said there is no evidence the capital needs less exhibition space.
"Britain’s competitors are currently expanding their own capacity because they understand the economic benefits these centres create. If the Mayor allows this proposal to go ahead he will be losing a £1bn a year contribution [which Earls Court makes] to the economy and will be damaging the UK's economic competitiveness," said Gavron.
"Losing Earls Court would be a huge set back for the London and UK economy. This economic benefit cannot and will not be replaced by a one-off construction project.
"The Mayor has just returned from a trip to India trying to attract investment into London. Yet, within the next couple of weeks he may remove one of London’s best shop windows for promoting national industries. Boris Johnson instigated the redevelopment of Earls Court by designating it an Opportunity Area. As chair of transport for London he owns the land and as Mayor he is currently due to make the final decision on the planning application."
Earls Court supporters argue that there is huge potential to grow the sector in the UK, with only 5% of Europe’s indoor exhibition space in the UK. This compares poorly with continental rivals such as Germany (which has 22%), Italy (14%) and France (13%).
Numerous organisations and individuals wrote to the secretary of state, Eric Pickles MP, in September asking him to call in the applications and decide to future of the exhibition centres himself. These include the Association of Event Organisers (AEO), local residents groups, local MP Andy Slaughter and London Assembly's Gavron.