George Best Belfast City Airport has denied it would have to close if Flybe were to fail.
Senior Conservative MP Tobias Ellwood named Belfast City and Southampton airports as possible candidates for closure if the ailing regional airline collapsed.
Speaking on BBC Radio 4's Any Questions?, the MP for Bournemouth East said: "If Southampton airport were to close because this airline went bust, or indeed Belfast City airport, these are changes which are very difficult to then reverse if they happened."
The pair have the highest proportion of Flybe operations among UK airports. At Southampton, 93% of flights are currently provided by Flybe; at Belfast City the figure is 81%.
Flybe was rescued by the government last week after its owners said it would fold if it was forced immediately to hand over air passenger duty (APD) collected from customers.
Mr Ellwood defended the Government's decision to rescue Flybe, saying: "What we didn't want to see is a sudden breakdown of the country coming to a complete standstill, and then having to recuperate which will take a couple of months, two or three months, possibly with the closure of a couple of regional airports.
"That would be very, very damaging indeed."
Belfast City Airport's spokesperson said: "There is, and will continue to be, a significant demand for the popular destinations we serve.
"We continuously work with airlines, new and existing, to ensure our route network meets the needs of our passengers and that our business remains a profitable one."
A spokesman for the Hampshire airport said: "Although there would be significant and potentially ongoing disruption, Southampton airport wouldn't close without Flybe.
"We continue to take prudent measures to consider all opportunities should any of our airlines be unable to fulfil their flight schedules."
Virgin Atlantic, Stobart Group and a US investment fund, Cyrus Capital, took over Flybe in March 2019. The intention is to rebrand the airline as Virgin Connect.
The government agreed to provide the loss-making airline with a tax "holiday" to defer payment of around £10m. It is also reviewing APD on domestic trips. The flight tax is widely expected to be cut in the Budget in March.
Belfast City's spokesperson said: "We welcome the arrival of Virgin Connect later this year and are confident the airline will provide a long-term, sustainable network to and from Northern Ireland."
Environmentalists have reacted furiously to the prospect of a tax cut. Director of Flight Free UK Anna Hughes said: "Perhaps Flybe's woes are a result of low taxes and the race to rock-bottom prices. Slashing APD is not the answer, not for the industry, and certainly not for the environment."