Concerns have raised over the use of "ultra-clean" buses as part of a proposed multi-million pound service in Dover.

Frustrated councillors have voiced their "disappointment" about the potential use of diesel-powered vehicles on the £16.1m Fastrack service running from Dover Priory station to a major housing scheme three miles away in Whitfield.

This comes a week after a report published to Kent County Council's (KCC) environment and transport committee described the buses as "ultra-clean".

KCC's Green Party leader Martin Whybrow (Ind), who has called for the use of more environmentally-friendly power, such as electric and hydrogen, said: "Diesel can’t fall into the category of ultra-clean, no matter how good it is."

He pointed out that KCC is working towards the UK national target of net-zero carbon emissions by 2050 and speaking to a panel of councillors, Cllr Whybrow said: "This is a really disappointing start to this service.”

National bus company, Stagecoach, will oversee the running of the Fastrack service if approved at the planning stage by KCC in January.

Matthew Arnold, the business development director at Stagecoach South East, defended the use of the Euro-6 vehicles in the short-term, which he described as having a "minimal" environmental impact in terms of emissions.

He also believes electric vehicles will "clearly" take centre stage in the years ahead and says Stagecoach wants to be on that path, but added that diesel remains "substantially cheaper".

Mr Arnold said: "In London, where Transport for London are facing a dire financial situation, there's a significant public subsidy supporting the operation of buses, even before the pandemic.

"In Kent, the overwhelming majority of bus services are commercial and self-sustaining."

The Fastrack plans have been in the works for several years and proposes to travel from the Folkestone Road station, stopping at Market Square, Dover Castle, the leisure centre and Whitfield, where 5,750 homes are to be built.

Supporters have said that the bus service will alleviate "awful" congestion in the town centre and the A2 while critics have raised concerns about harmful emissions.

A KCC officer said Euro-6 diesel buses was not where the council wanted to be but it would be expensive to go electric at the start.

The KCC transport committee was told: “We want to be the cleanest fleet possible, however we are building from the ground at Dover Fastrack and we have got a limited amount of funding to get the service up and going."

Cllr Nigel Collor, who is Dover District Council's transport cabinet member, said he wanted the scheme to be as "green as possible" but warned about the logistical difficulties faced by buses going up the town's "steep" Castle Hill.

However Cllr Rob Bird (Lib Dem), who is the main opposition leader at County Hall, said he shared the "disappointment" of Cllr Whybrow that there was not a firm commitment to "ultra-clean" buses from "day one".

The service could be introduced from 2023 if plans are approved by KCC's planning committee on January 13, having been pushed back from December due to objections. The scheme will be funded by the government.