The UK security minister, Ben Wallace, has pointed to Russia as being responsible for the nerve agent poisonings in Wiltshire and called on Moscow to help authorities keep the people of Britain safe by giving information.

An urgent investigation is under way to discover how a British couple were left critically ill by novichok, the same military-grade nerve agent that nearly killed the former Russian spy Sergei Skripal and his daughter, Yulia, four months ago. The home secretary, Sajid Javid, has been chairing a meeting of the government’s emergency Cobra committee and is to make a statement to the Commons afterwards.

Asked whether Russia could be responsible, Wallace said: “Based on the evidence we had at the time of the Skripal attack, the knowledge they [Russia] had developed novichok, they had explored assassination programmes in the past, they had motive, form and stated policy, we would still assert to a very high assurance that the Russian state was behind the original attack.

Wiltshire incident Q&A: is there any link to the Skripal case? Read more

“The working assumption would be these are victims of the consequences of the previous attack or something else but not that they were directly targeted. That could change.”

Speaking on BBC Radio 4’s Today programme, he said: “This [the Skripal incident] was a brazen and reckless attack at the heart of a very peaceful part of the UK. That is part of the anger I feel at the Russian state. They chose to use a very, very toxic, highly dangerous weapon. Novichok in the smallest form can injure thousands of people.”

He continued: “The Russian state could put this wrong right. They could tell us what happened, what they did and fill in some of the significant gaps we are trying to pursue. We have said they can come and tell us what happened. I’m waiting for the phone call from the Russian state. The offer is there.”

Wallace said he could not be absolutely sure the people of Salisbury and surrounding areas were safe, given the early stages of the investigation. “Until we can get to a place where we know much more, then our levels of assurances will remain low risk but not zero risk,” he added.

The Kremlin described the Amesbury poisonings as “disturbing” and said Russia wished the victims a speedy recovery. But Vladimir Putin’s spokesman, Dmitry Peskov, told reporters in Moscow that Russia had so far received no appeal from the UK in relation to the incident.



Play Video 2:35 CCTV footage shows novichok victim day before attack – video report

Theresa May said on Thursday that Salisbury and the wider area remained “very much open for business”. A No 10 spokesman said the latest incident did not mean the cleanup operation after the Skripal poisonings had been incomplete.

The prime minister was not at the Cobra meeting because she was en route to Berlin. Ministers attending included the foreign secretary, Boris Johnson, the defence secretary, Gavin Williamson, and the environment secretary, Michael Gove.

In a statement, May said: “All of my thoughts today are with the victims and with the people of Amesbury and Salisbury. After the brazen and reckless attempt to murder the Skripals with novichok in March, the community showed tremendous fortitude, patience and resilience.”

Extending her thanks to residents, local businesses and the emergency services, she added: “The massage from Salisbury is clear: it is very much open for business. The government will continue to provide every support to the local community.”

Asked whether people could be reassured given the new case, May’s spokesman said: “The advice from chief medical officer was clear that the risk to the public is low. Equally the chief medical officer was clear that in terms of the sites involved in the Skripal incident they have now been decontaminated.”

The international development secretary, Penny Mordaunt, is visiting Salisbury for the government on Thursday. She had been scheduled to visit a landmine charity, and then meet people involved in the nerve agent operation, May’s spokesman said.

Britain’s top counter-terrorism officer, Neil Basu, announced on Wednesday night that expert scientists in chemical warfare at the Porton Down laboratory had established that novichok caused the collapse of Dawn Sturgess, 44, from Salisbury, and Charlie Rowley, 45, of Amesbury.

Play Video 0:51 Police say Wiltshire couple were poisoned by novichok – video

They were taken ill at their home on Saturday, eight miles from the Salisbury home of Sergei Skripal. The Skripals were attacked in March with novichok, which police said was smeared on to their front door.

Initially police thought that drugs had caused Sturgess and Rowley’s severe illness. Basu said investigators and scientists did not know how the British couple had been exposed to the nerve agent. Paramedics were first called to a home on Muggleton Road in Amesbury at 10.15am on Saturday after Sturgess collapsed. Five hours later Rowley was taken ill.

They were taken to the Salisbury district hospital, where the Skripals were also treated.

Basu said: “From initial assessment it was thought that the two patients had fallen ill after using drugs from a potentially contaminated batch. However ... due to concerns over the symptoms the man and woman were displaying, samples from both patients were sent to Porton Down laboratory for analysis.

Quick guide What is novichok? Show Hide Novichok refers to a group of nerve agents developed by the Soviet Union in the 1970s and 80s to elude international restrictions on chemical weapons. Like other nerve agents, they are organophosphate compounds, but the chemicals used to make them, and their final structures, are considered classified in the UK, the US and other countries. The most potent of the novichok substances are considered to be more lethal than VX, the most deadly of the familiar nerve agents, which include sarin, tabun and soman. Novichok agents work in a similar way, by massively over-stimulating muscles and glands. Treatment for novichok exposure would be the same as for other nerve agents, namely with atropine, diazepam and potentially drugs called oximes. The chemical structures of novichok agents were made public in 2008 by Vil Mirzayanov, a former Russian scientist living in the US, but the structures have never been publicly confirmed. It is thought they can be made in different forms, including as a dust aerosol. The novichoks are known as binary agents because they only become lethal after mixing two otherwise harmless components. According to Mirzayanov, they are 10 to 100 times more toxic than conventional nerve agents. Photograph: Matt Cardy/Getty Images Europe

“Following the detailed analysis of these samples, we can confirm that the man and woman have been exposed to the nerve agent novichok, which has been identified as the same nerve agent that contaminated both Yulia and Sergei Skripal.”

Basu said on Wednesday evening that no one else had complained of the symptoms associated with novichok poisoning. A senior government source told the Press Association it was believed there was cross-contamination of the same batch of nerve agent involved in the “reckless” Salisbury attack, as opposed to a secondary attack.