The home secretary, Amber Rudd, has condemned the poisoning of a former Russian double agent in Salisbury as a “brazen and reckless” attempted murder.
Updating the House of Commons on the nerve agent attack, Rudd said Sergei Skripal, 66, and his daughter, Yulia, 33, remained “unconscious and in a critical but stable condition”.
She confirmed that a police officer who came to their aid was in a serious but stable condition but was “conscious, talking and engaging”.
She did not reveal the specific nerve agent involved but confirmed it had been “tested by experts at the Defence, Science and Technology Laboratory at Porton Down, who are world renowned experts in this field”. She added: “That forensic analysis has revealed the presence of a nerve agent and the incident is therefore being treated as attempted murder.”
Rudd was speaking as forensic officers began a major search for evidence about the attack in Skripal’s home in Salisbury. They also cordoned off the graves of Skripal’s wife and son. Luidmila Skripal died of cancer in 2012, aged 59. His son Alexander, who is buried in the same Salisbury cemetery, died a on 1 March last year in St Petersburg.
Amid mounting speculation that the attack was ordered by the Kremlin, Rudd said: “The use of nerve agent on UK soil is a brazen and reckless act. This was attempted murder in the most cruel and public way.”
But she added: “If we are to be rigorous in this investigation we must avoid speculation and allow the police to carry on their investigation. The investigation now involves hundreds of officers following every possible lead to find those responsible.
“We are committed to doing all we can to bring the perpetrators to justice, whoever they are and wherever they may be. As the foreign secretary made clear, we will respond in a robust and appropriate manner once we ascertain who was responsible.”
Downing Street would not be drawn on whether the sickness of the police officer would escalate the government’s response. “It’s important we establish the facts,” a Downing Street spokesman said.
He said the attack in Salisbury was “an appalling and reckless crime and the public will rightly want those responsible to be identified and held to account.”
He added: “The prime minister wishes again to send her personal thanks to the police and emergency services for the typical courage they have shown in responding to this attack. She would also like to thank the people of Salisbury for their support in recent days.”
Speaking earlier on BBC Radio 4’s Today programme, Rudd said the officer was not in intensive care, but his condition was serious.
She suggested that experts had identified the substance involved in what she described as a “very, very serious attack”. But she refused to be specific. “For now all we are going to say is that it is a nerve agent … It is very rare,” she said.
Rudd said detectives had divided the investigation into three separate sites: the Skripals’ Salisbury home; the city’s Mill pub, where they had been drinking; and the Zizzi restaurant where they had eaten before collapsing on a park bench.
Unlike in the case of Alexander Litvinenko, poisoned with a slow-acting radioactive cup of tea, detectives got to the scene in Salisbury quickly. Hundreds of officers were now working around the clock, Rowley said. They were examining CCTV footage from the city centre and building a detailed timeline of events, he added.
Speaking to ITV’s Good Morning Britain, Rudd said: “Whatever attribution takes place in the future we have to make sure we have all the evidence. The key thing is to have a cool head and allow [those investigating the incident] to continue that job, which they are doing with speed and with detail and with the support of professionalism we can expect.”
Asked if she believed the poisoning was a Russian assassination attempt, Rudd said: “I’m determined to wait before any attribution [is made] until we have the facts. I’m completely confident that the police will be able to get that.”
Nerve agents are not hard to make in principle, but in practice it takes specialised facilities and training to mix the substances safely. The raw materials themselves are inexpensive and generally not hard to obtain, but the lethality of the agents means they tend to be manufactured in dedicated labs. The main five nerve agents are tabun, which is the easiest to make, sarin, soman, GF and VX. The latter was used to kill Kim Jong-nam, the half-brother of the North Korean leader, Kim Jong-un, at Kuala Lumpur airport last year. VX is particularly stable and can remain on clothing, furniture and the ground for a long time without proper decontamination.
All pure nerve agents are colourless organophosphorus liquids which, after they were discovered to be highly poisonous in the 1930s, became the dominant chemical weapons of the second world war. Once made, the substances are easy to disperse, highly toxic, and have rapid effects. Most are absorbed swiftly through the skin or inhaled, but they can also be added to food and drink.
The agents take their toll on the body by disrupting electrical signals throughout the nervous system and the effects are fast and dramatic. Victims find it increasingly hard to breathe. Their lungs produce more mucus which can make them cough and foam at the mouth. They sweat, their pupils constrict, and their eyes run. The effects on the digestive system trigger vomiting. Meanwhile the muscles convulse. Many of those affected will wet themselves and lose control of their bowels. At high doses, failure of the nerves and muscles of the respiratory system can kill before other symptoms have time to develop. There are antidotes for nerve agents, such as oxime and atropine, which are particularly effective against VX and sarin, but they should be given soon after exposure to be effective.
The defence secretary, Gavin Williamson, told the programme that Russia was “becoming an ever-greater threat”.
But he declined to say whether he held Russia responsible for the attack, saying only: “What’s happened is absolutely disgusting and it is so important we give the police the space and opportunity to do a proper and thorough investigation.”
He paid tribute to the police officer who went to the Skripals’ aid as “someone who is doing their public duty, keeping Britain safe and has become a victim of this dreadful, dreadful attack”.