Questions have been raised over how Gloucestershire’s new 13-tonne pothole-busting JCB machine was bought from a firm which is a major financial backer of the Conservative Party.

Gloucestershire County Council approved a “last minute” amendment to its budget earlier his year to spend £500,000 on new machinery including a JCB Pothole Pro – the recommended retail price of the JCB machine is understood to be £200,000.

However, concerns have been raised over the lack of scrutiny into the purchase ahead of the machine being bought.

The Conservative Party has accepted more than £1.3m from JCB and the Bamford family, which runs the company, according to analysis by openDemocracy.

Liberal Democrat Councillor David Willingham raised concerns about the Pothole Pro purchase at the audit and governance committee meeting on April 25.

He said thousands of pounds had been donated to the Conservatives and asked for the procurement to be “properly audited for probity reasons”.

However, Tory Councillor Andrew Gravells objected to Cllr Willingham’s comments.

He said it seemed like the Liberal Democrat was making a political point just before the local elections.

Cllr Willingham said: “The JCB Pothole Pro didn’t go through budget scrutiny and the budget amendment was made at the last minute by the administration and it just says to procure a JCB pothole pro as part of a pioneering approach to potholes.

“It hasn’t gone through scrutiny and there are reports that the pothole pro is expensive and doesn’t actually do the job it claims to do.

“And in light of the very opaque procurement process, that seems to be outside of the contract procurement rules so no-one has looked at it, and the fact that JC Bamford excavators Ltd, as in JCB, has given thousands of pounds of predominantly to the Conservative and Unionist Party, including donations in Cheltenham, could we have this properly audited just for probity reasons?

“We want to ensure this money has been spent on a product that is fit for purpose and not as part of a possible quid pro quo for political donations.”

Cllr Gravells interjected to ask the chairman “what on earth was going on”. He asked if it was normal practice for a committee member to ask public written questions of his own committee.

The Abbey councillor, who chairs the health overview and scrutiny committee, said if members have a question on his committee they write to the relevant officer.

“I’m not sure why our time is being taken up on what seems to be a political issue just before the local elections,” Cllr Gravells said.

Chairman John Bloxsom said public and member questions are allowed at the audit and governance committee.

“I understand that,” Cllr Gravells replied. “But why would an elected member want to put in a written question when they are already a member of this committee. I’m slightly suspicious of the motivation here when we are starting to gear up into the local elections.

“What on earth is going on? That’s nonsense.

“If every member of this committee put written questions onto you, that would be all we’d do all day.

“I’m not trying to cover anything up – I do not know what the councillor is trying to achieve but I suggest, with respect, he is doing it the wrong way.”

Councillor Colin Hay (LD, All Saints and Oakley) said the provision for questions is there to raise issues which are not on the agenda.

“I’m surprised a chairman of a committee doesn’t understand that,” he said.

Cllr Bloxsom said budget amendments can be moved without notice. “If that has happened on this occasion that will be why there was no prior scrutiny,” he said.

Councillors Bloxsom, Gravells, Willingham are district council candidates for the elections in Stroud, Gloucester and Cheltenham respectively.