Ryanair's chief executive Michael O'Leary has questioned Clare County Council's support for the airline's services at Shannon after a member of a council delegation refused to fly to Madrid with the airline.
Mr O'Leary has written to Clare's mayor, Cllr Flan Garvey (FF), pointing out that Ryanair had created substantial benefits for Shannon and the region.
It follows the council accommodating a member of the council delegation to fly Aer Lingus to Madrid as she refused to fly with Ryanair.
The council party of 12 flew Ryanair from Shannon to Madrid for a five-day educational field trip. However, academic Dr Anne Clune, who is not a councillor, took two flights to get to Madrid as she refused to fly with Ryanair over its non-recognition of unions.
Ryanair has 27 scheduled services from Shannon.
A council spokeswoman said there was a slight difference in the cost arising from Dr Clune's decision to fly Aer Lingus. Dr Clune paid the difference.
Cllr Garvey said yesterday: "Mr O'Leary suggested that the council paid extravagant money to pay for Dr Clune. The council did not.
"It paid exactly the same as if Dr Clune was travelling Ryanair and Dr Clune paid the rest. Mr O'Leary questioned the council's support of Shannon. We are totally supportive of Ryanair and I will be telling him that . . . I support Ryanair as best I can all the time.
"There is no question whatsoever of Clare County Council not supporting Ryanair. We welcomed them into Shannon. They are giving tremendous service out of Shannon."
He said the decision to accommodate Dr Clune was a one-off and he would be personally responding to Mr O'Leary.
A spokesman for Ryanair said it would be inappropriate to reveal the contents of Mr O'Leary's letter. "We have already expressed our surprise at the local authority facilitating Dr Clune as it was a waste of tax-payers' money."