OPPONENTS of an airport at Cliffe were given a boost today when the nation's leading employers' organisation came out against it. The Confederation of British Industry is backing extra runways at Heathrow and Stansted rather than a new facility on the Hoo Peninsular.

In a document sent to the Government, the CBI, which has a regional base in Sevenoaks, says it would not be cost effective to develop a new site from scratch with all the supporting infrastructure it would entail.

Nigel Bourne, the CBI's Kent-based regional director who has spoken at public meetings about the potential business and economic gains from an airport at Cliffe, said UK competitiveness is under threat because of failure to provide additional airport capacity as worldwide demand for aviation grows. He added that airport expansion was crucial for the future success of the UK economy.

" We either respond to growing demand or face being left behind," he said. "In addition, Britain's position as a world leader in aviation is under threat unless we act. Foreign competitors would welcome our dissatisfied customers with open arms.

"The South East has the strongest market for UK aviation and the greatest concentration of airlines. It must be maintained as a globally competitive hub to provide vital access to international markets, encourage inward investment and support tourism."

The CBI says three new runways will be needed in the South East in a broad package using all the UK's existing aviation infrastructure. It says the first should be at Heathrow by 2015, the second at Stansted by 2020, and a third at either Gatwick or Stansted by 2030.

The CBI believes that the UK needs Heathrow to remain a global hub airport with capacity to offer the number of flights and destinations business needs. A hub airport is crucial to businesses throughout the UK as it links regional airports with major international routes.

The CBI claimed that expansion at Heathrow was essential to halt the relative decline of what was once the second best-served airport in the EU but is now only the fourth.

It also called on the Government to develop regional airports. Mr Bourne said: "The expansion of regional airports is absolutely vital to the development of the UK as a modern and efficient place to do business. Though the South East plays the lead role in UK aviation, it must be supported by a host of regional star performers."