The Joint Combat Aircraft is to replace the Harrier

Newquay, which operates from RAF St Mawgan, relies on essential services from the RAF such as air traffic control and fire and rescue.

But St Mawgan is due to be mothballed in 2007.

And MP Matthew Taylor says it is unlikely to be a base for the new Joint Combat Aircraft (JCA).

St Mawgan is one of five RAF bases earmarked as possible bases for the JCA, a replacement for the Harrier, in 2012.

A final decision is now expected to be announced on Thursday.

But Mr Taylor said that noise levels of the JCA, double that of existing fighter aircraft, probably ruled out civilian operations at Newquay.

Lossiemouth 'front-runner'

He said: "If I was blunt I would say I don't think we are going to get the JCA anyway.

"The noise levels probably make it impossible to operate out of RAF St Mawgan.

"It looks like RAF Lossiemouth is the front runner, that's certainly the belief in Scotland.

"So the question for us may be 'Is there anything else we can do to keep Newquay Airport open if we haven't got the JCA there?'."

He said it was crucial that the county council, which owns the loss-making Newquay Airport, prepared a strategy to keep it running.

He spoke after Armed Forces Minister Adam Ingram told him in the Commons on Monday that there would be no further Ministry of Defence funding if the RAF withdrew from St Mawgan.

Mr Ingram added that the county council had signalled its opposition during consultation on the JCA being based at St Mawgan because of the noise impact on local residents.

But the county council, which sees Newquay as essential for Cornwall's economy, rejected the claim on Tuesday.

It said in a statement: "Our priority is to create a thriving airport, so we actually sought more information on how the military and civil airports would work together, and reassurance on noise levels, but did not reject St Mawgan's nomination as a potential JCA base.