Councillors in Carmarthenshire have criticised a reduction of services on a rail line named as one of the best in Europe, fearing its long-term future could be in jeopardy.

The Heart of Wales Line runs from Swansea to Llanelli, where the train reverses and then heads north.

The 121-mile route winds through Carmarthenshire, Powys and Shropshire, terminating at Shrewsbury. It is popular with tourists and also used by commuters.

Operator Transport for Wales (TfW) has said services will reduce from five to four per day from December this year, along with the removal of two late evening services to Llandovery and Llandindrod Wells. Bus options, said TfW, were being explored.

A motion backed by Carmarthenshire councillors claimed the Heart of Wales Line had suffered from under-investment for decades and that this, along with service reductions, could jeopardise its long-term future. It said the level of rail investment in Carmarthenshire was “in stark contrast” to the money being funnelled into South-East Wales, and it called on the Welsh Government to review TfW’s decision.

Independent Llandeilo councillor Edward Thomas, who brought the motion to full council with Plaid Llangadog councillor Andrew Davies, felt it was “the start of a slippery slope”.

He said: “Residents along the line are experiencing delays, cancellations, no replacement buses and a lack of information.” This meant onward connections, he said, were being missed.

Cllr Thomas said there were very few days in the last five months when all the trains were on time. He said one constituent described the rolling stock as “clapped-out British Rail 153 Sprinter trains which are over 40 years (old) and have a poor service record”.

Cllr Thomas said transport professor and consultant Stuart Cole, of the University of South Wales, had also expressed concerns about the service reductions and that a Heart of Wales Line passenger group was lobbying for a reversal of the decision.

Labour councillor Kevin Madge said two years ago the Welsh Government pledged there would be 30% more rail services in Wales by 2025 compared to 2018, benefiting from £800 million of new rolling stock. “More money has gone into the services,” he said. Further funding of £125 million in TfW, he said, was announced last autumn.

According to Cllr Madge, Wales has received 1.5% of UK rail investment via Westminster despite having 5% of its population, whereas Scotland – with 8% of the population – has had 8% of the investment. He said the motion would be supported by Labour councillors because of the Heart of Wales Line’s importance to the area, but he said a fair funding formula was needed and that he hoped things would improve now that Labour was in power in London.

Labour group leader, Cllr Deryk Cundy, said no-one wanted the line to be lost. “A few years ago I understood they were going to expand it – I don’t know what’s changed,” he said.

Independent councillor Rob James said rail services had to be reliable, affordable and frequent, and that less frequent services meant fewer passenger numbers. “What the Welsh Government needs to be doing is increasing services, getting people more on the trains and actually impacting the climate change agenda,” he said.

Plaid councillor Alun Lenny said Wales was not being funded according to its needs. “Until we get power in Wales over the two great economic levers of energy and natural resources I’m afraid that very little will change, but during this honeymoon period I will give my Labour colleagues the benefit of the doubt,” he said.

The Heart of Wales Line was named by travel experts, the Lonely Planet, as among the 10 best train rides in Europe. “Expect a spectrum of scenery, alternating from the sand-edged estuaries of South Wales, via bucolic farming towns and tracts of forest and hill country you probably never knew existed, through to one of England’s prettiest medieval cities,” it said.

The Local Democracy Reporting Service contacted the Welsh Government and TfW, which referred to the announcement in April to reduce Heart of Wales Line services – a decision which took into account changing passenger demand. The timetable review is also leading to more services and longer trains along some routes.

Speaking at the time, TfW planning and performance director Colin Lea said: “The proposed new timetables will provide us with more resilience in the winter period and meet changed travel demands post Covid. Nearly every service that TfW operates requires public subsidy, and as a responsible operator it’s imperative for TfW to balance the needs for a regular, robust and reliable service with available budgets to deliver value for taxpayers and more sustainable transport.”