The Welsh Government says it has to cut bus funding in April because its transport budget is under pressure, but it will continue paying £1.6m a year for the flights between Holyhead and Barry.
The air service carried just 10,000 passenger journeys last year – compared with 114 million on Welsh buses.
Eluned Parrott, Welsh Liberal Democrat shadow transport minister, said: “We all know that difficult choices have to be made in these tough economic times. I would hope that with hindsight even the Welsh Labour Government would accept that it has had the wrong transport spending priorities. It’s a scandal that the Welsh Government are forking out £160 per passenger on flights, while at the same time punishing the most vulnerable in our society by scaling back on bus subsidies.”