The police and crime commissioner for Wiltshire has said he is determined to ensure his force does not pay any of the £10m cost of responding to the nerve agent poisonings in Salisbury.

Angus Macpherson said the poisonings had led to “an extraordinary period of demand” on Wiltshire police and the total projected cost for the force was £10m. So far the Home Office has reimbursed £6.6m.

“It’s important to me that these additional costs are not shouldered by Wiltshire police,” he said. “I have been in frequent contact with the Home Office and I am pleased that the policing minister Nick Hurd has recognised the financial implications of the operation. It remains an absolute priority for me to recoup these costs.”

Macpherson said he had been impressed by the hard work and dedication shown by officers, staff and volunteers after the attempted murder of the Russian former spy Sergei Skripal and his daughter, Yulia, in March.

“They worked tirelessly to ensure the public were kept safe,” he said, adding that the poisonings had highlighted how emergency workers put themselves in unknown and potentially dangerous situations every day to help and protect the public.

Macpherson criticised the government over the way it funds the force and said that if changes were not made it would become increasingly difficult to sustain the current performance.

“Wiltshire still receives unfair funding from central government. This means we have less money to spend protecting the public than almost all other areas in England and Wales,” he said. “The government needs to reform the formula which allocates funds to me. We have been historically under-funded and the people of Wiltshire and Swindon deserve a fair deal.

“We face the same complex range of threats that bigger and better-funded forces face – a fact brought home to us all very powerfully with the Salisbury chemical weapon attack.”

He said it did not make sense to give Wiltshire £151 per person to spend on policing, £20 less than the national figure of £171.

“The people of Wiltshire and Swindon and those served by other smaller rural forces are getting short-changed,” Macpherson said. “I have less money to keep the public safe than all of the PCCs who border us. It’s a policing postcode lottery and is unacceptable.”

A Home Office spokesperson said: “Police have the resources they need to carry out their vital work and we have provided a strong and comprehensive settlement that is increasing total investment in the police system by over £460m in 2018/19, including increased funding for local policing through council tax precept.

“Wiltshire police will receive £109.2m in direct resource funding in 2018-2019, including council tax precept – a cash increase of £4.1m compared with 2017/18.

“We provided £1.6m in special grant for 2017-18 to cover extra costs incurred by Wiltshire police associated with the incidents in Salisbury and Amesbury. We have provided further interim special grant payments totalling £5m in 2018/19, taking the total provided to £6.6m.”