The airport will be without a licence until 19 December
Cornwall County Council has "seriously damaged" the county's image over the Newquay Airport fiasco, an MP said.
Mark Prisk, Conservative Shadow Minister for Cornwall, spoke after the airport was closed until 19 December.
The council, which owns the airport, had been due to take over air traffic operations from the RAF on 1 December.
But as the Civil Aviation Authority (CAA), which is responsible for safety, did not grant it a licence it has had to cancel all flights in and out.
It is believed about 209 departures and 7,000 passengers could be affected by the temporary closure.
Mr Prisk told BBC News: "Cornwall is a great place to live and work. My worry is that people will look at this and think that here is a county council that can't even run basic contracts.
"Why would I want to invest there? Why would I want to have jobs there?
"I hope that isn't the case, but my fear is that Cornwall County Council may have seriously damaged the excellent image that Cornwall has."
My fear is that Cornwall County Council may have seriously damaged the excellent image that Cornwall has
Andrew Mitchell, the county councillor with responsibility for the airport, said: "The county council was brave enough to take on a unique challenge - to take a military air base at RAF St Mawgan and turn it into a civilian aerodrome.
"That was a huge challenge and we have managed that up to date, and at the last minute there has been one hitch which unfortunately has tripped us up.
"I am really sorry for people who are going to be hugely inconvenienced."
The county council is laying on transport back to Newquay for passengers diverted to other airports because of the closure, at a cost which is expected to run into thousands of pounds.
Mr Mitchell said: "We have independently and without obligation decided to get those people back home to Cornwall."
The council is not ruling out legal action to recover its costs.
Mr Mitchell said CAA inspectors were meeting the authority on Friday and the council would make make "whatever resources are available" to re-open the airport on 20 December.