Cardiff Airport's Sunday Cardiff Bus service scrapped
A bus service which operates four times a day to Cardiff Airport is to be scaled back.
Cardiff Bus is dropping the Sunday X91 service from next month as part of the company's review of its timetables.
Opposition parties said transport links to the struggling airport should be improved, not cut, and it was "terrible news" for surrounding communities.
Cardiff Bus said it was too "commercially sensitive" to comment further.
But Gareth Stevens, business development manager at the bus firm, confirmed the Sunday service will end.
He added: "Cardiff Bus is however pleased to confirm it will be maintaining its Monday to Saturday services to the airport.
"We have provided a Sunday service to and from Cardiff Airport for a very long time but ultimately the success of the route is directly affected by the success of the airport.
"We cannot comment further on this as it is commercially sensitive."
The Welsh government agreed a deal to buy the troubled airport in March after a slump in passenger numbers. bought for £52m.
Figures for the year up to March 2013 show the number of passengers who used Cardiff Airport dropped below the one million mark for the first time in recent years. It's peak was two million in 2007.
Eluned Parrott, Welsh Liberal Democrat AM for South Wales Central, said her party had been calling for a direct and high quality route between Cardiff city centre and the airport for many years.
She said: "With the airport now owned by the Welsh Labour government, you would have thought that improving transport links would be one of their top priorities.
"If we are to see an upturn in the airport's fortunes we need to be able to get passengers there every day of the week, particularly if we want to develop the important weekend break market from Europe."
Mrs Parrott said the announcement was "terrible news" for communities that use the service.
"The X91 isn't just an airport bus route, it serves a number of communities in the Vale of Glamorgan who have little or no access to other public transport," she added.
"The removal of this route could have a devastating affect on the lives of many elderly and vulnerable people in the area."
Welsh Conservative leader Andrew RT Davies AM called the decision "bizarre".
He said: "This is unacceptable from the Welsh government, and even more so now that they own the airport.
"The loss of the X91's Sunday service will have a real impact on passengers from Cardiff and the Vale, particularly elderly and less well-off.
"It seems bizarre that the Welsh Labour government can assume ownership of the airport without giving due attention to the transport links that service it and it is quite astonishing that they haven't even bothered to respond to Cardiff Bus's requests for discussions - some nine months later."
The Welsh government said it was "actively exploring" enhanced bus routes from Cardiff to the airport and the enterprise zone.
"These new services are planned to be in operation from August," added a spokesperson.