Highland MSP Donald Cameron has demanded action to protect flights to Coll, Colonsay and Tiree after receiving details of the financial challenges facing the service.
Argyll and Bute council has written to the Tory MSP confirming flights may cease, at least temporarily, if a new operator is not found when the current contract ends next month.
The letter from the local authority’s head of Economic Development Fergus Murray said the council had to make £50 million of savings over the last nine years and was facing a £8m funding gap this year.
Despite the pressure from cuts, Mr Murray said Argyll and Bute valued the air service and was giving £2.04m to the service over the next four years.
The council has put the flights, which connect the isles to Oban, out to tender. The current service, run by Hebridean Air Services, ends on May 15.
However talks to renew the contract have stalled over money with Hebridean Air Services saying it is being offered £200,000 less per year than they currently receive.
Mr Murray’s letter warned that there could be a period where “services are not available” if a new operator succeeds in winning the tender.
He added the council was still seeking an “interim solution” with Hebridean Air Services.
Mr Cameron said: “This air service is a lifeline for the communities that it serves on Coll, Colonsay and Tiree. Among the people who use it are pupils attending high school in Oban and medical professionals.
“It is clear from this letter that funding air transport links to these islands presents major financial challenges for the council, which have been made much worse by years of unfair financial settlements from the Scottish Government.”
Depute council leader Gary Mulvaney said: “Having suffered the third largest cut in core revenue funding in Scotland in the last five years, it is a massive challenge to fund services that are non-statutory. If the Scottish Government genuinely values these air and ferry services, they should step up to the plate and fund them properly or even better run them themselves”.
A Hebridean Air spokesman said: “We are currently in dialogue with the council to see if we can bridge the gap between May 15 and the new contract on 16th October. But they have reduced the subsidy and we were unsuccessful in our tender.”