Policing costs related to the novichok incidents in Salisbury and Amesbury have surpassed £10m.

Wiltshire police had to call in help from 40 other forces as they dealt with the poisoning of the Russian former spy Sergei Skripal and his daughter, Yulia, in Salisbury in March, followed four months later by the poisoning of Charlie Rowley and his partner, Dawn Sturgess, who died.

It is estimated that the cost of bringing in officers from other forces will be more than £7m, and more than £1.3m has been spent on overtime within Wiltshire police. This was to ensure officer numbers could be maintained across the area while dealing with the attacks.

Other costs include £347,000 spent on disposing of and replacing a number of police vehicles. The £10m total does not include the cost of the Metropolitan police’s investigations.

The police and crime commissioner for Wiltshire and Swindon, Angus Macpherson, said the government should cover the bill. “For our force to find itself at the centre of two major incidents in such a short space of time is somewhat unimaginable and we have endured significant costs because of the scale of the investigation,” he said.

“I am grateful that the government has already pledged £4.1m towards the costs incurred by Wiltshire police during the investigation into the attack on Yulia and Sergei Skripal. I fully expect all costs associated with these unparalleled incidents to be met by the government.”

Wiltshire police had to cancel officer rest days and put annual leave requests on hold, and also brought in private security to guard cordons.

The chief constable, Kier Pritchard, said: “Our mutual aid arrangements mean that other frontline policing duties have remained unaffected in Wiltshire despite us dealing with two internationally significant incidents in just four months.

“I am assured that the commissioner will continue his dialogue with the government to ensure that Wiltshire police and the communities we serve are unaffected by these growing costs.”

Skripal, a former colonel in Russian military intelligence, and his daughter were found unconscious on a bench in a shopping centre after being exposed to novichok in March. Police and intelligence officers believe the nerve agent had been sprayed or smeared on to the front doorknob of Skripal’s home. DS Nick Bailey from Wiltshire police was also taken to hospital after being exposed to the agent.

Police are working on the assumption that a bottle containing the novichok was dropped somewhere in the city and later picked up by Rowley, who gave it to Sturgess.

Russia has consistently denied British accusations that it orchestrated the attacks and has waged a furious campaign of counter-accusation, including suggestions that the UK is holding the Skripals against their will and denying them Russian consular assistance. Relations between the two countries are now at their worst since the end of the cold war.

After months of painstaking investigation by hundreds of officers from the police and the intelligence agencies, the British government is poised to submit an extradition request to Moscow for two Russians it suspects of carrying out the attack.

Russia is certain to reject the request, prompting another round of diplomatic expulsions.

On Wednesday the US announced it would impose restrictions on the export of sensitive technology to Russia because of its use of novichok in Britain. These will be followed by more sweeping measures including suspending diplomatic relations and revoking Aeroflot landing rights if Russia does not take “remedial” action within 90 days.

The US has also called on Russia to open up its scientific and security facilities to international inspections to assess whether it is producing chemical and biological weapons in violation of international law. Moscow is not expected to agree to the measures.