Sergei Skripal 'poisoning': Police examining CCTV footage taken from alleyway near Zizzi restaurant

Restaurant and pub closed as work to identify 'unknown substance' continues

Police investigating the suspected poisoning of a former Russian spy are examining CCTV believed to show the last movements of Sergei Skripal and his daughter before they fell unconscious.

A man and woman were shown walking through an alleyway outside a Zizzi branch in Salisbury less than half an hour before police were called to the major incident.

Police have closed off the restaurant, a pub and the nearby bench where 66-year-old Mr Skripal and his daughter, Yulia, were found severely ill.

They remain in a critical condition in intensive care after being exposed to an "unknown substance" that triggered an alert over hazardous material in the Wiltshire city.

Detectives visited a nearby gym Snap Fitness 24/7, and took away CCTV footage of a man and woman walking through an alley at 3.47pm on Sunday.

Cain Prince, the manager, said: "Police had a good look at the footage and were interested in these two people. It was the only image they took away.

"They wanted a list of everyone in the gym between 3pm and 4pm as well."

At 4.15pm on Sunday, police were called by a member of the public concerned for Mr Skripal and his daughter's welfare. They were found unconscious on a bench, with no visible injuries.

Witness Freya Church said: “There was a couple, an older guy and a younger girl. She was sort of leant in on him, it looked like she had passed out maybe. He was doing some strange hand movements, looking up to the sky.”

Boris Johnson, the Foreign Secretary, confirmed the victims' identities and told the House of Commons Britain would impose fresh sanctions on the Russian government if a link is proven.

“It is too early to speculate as to the precise nature of the crime or attempted crime that has taken place in Salisbury, but I know members will have their suspicions and what I will say is that if those suspicions prove to be well-founded than this Government will take whatever measures we deem necessary to protect the lives of people in this country, our values and our freedoms,” he said.

“Though I am not now pointing fingers, I say to governments around the world that no attempt to take innocent life on UK soil will go either unsanctioned or unpunished.”

Wiltshire Police said several members of the emergency services were themselves taken ill after responding to the incident, with one remaining in hospital.

"As part of our enquiries, a number of scenes have been secured," a spokesperson added. "These include the Zizzi restaurant on Castle Street and The Bishop's Mill pub in The Maltings. At this time, we cannot confirm how long these cordons will remain in place.

"The advice from Public Health England remains that, based on the evidence to date, currently there doesn't appear to be any immediate risk to public health.

"The public are likely to continue to see an increased police and emergency services presence in the city centre today to provide reassurance."

Police officers stand at crime scene tape, as a tent covers a park bench on which former Russian inteligence officer Sergei Skripal, and a woman were found unconscious after they had been exposed to an unknown substance, in Salisbury, Britain (REUTERS/Toby Melville)

Relatives told the BBC that Ms Skripal, 33, was in Britain to visit her father. His son is said to have died in non-suspicious circumstances while on holiday in Russia last year.

Mr Skripal initially lived in Salisbury with his wife, who passed away in 2012.

The Zizzi branch has been shut down and a police officer remained outside in an unmarked car through Monday night.

Officers spoke to restaurant staff as specialists worked in tents around the area where the pair were found.

Mr Skripal is a former Russian double agent, who was convicted in his home country after spying for the UK.

Once a colonel in Russia's GRU military intelligence service, he was given refuge in Britain after he was exchanged in 2010 for Russian spies caught in the West as part of a Cold War-style swap in Vienna.

The case has been compared to that of former FSB officer Alexander Litvinenko, who died after being poisoned with radioactive polonium-210, which was believed to have been put in his tea.

The Independent understands that police are looking for similarities between the cases and the modus operandi used.

Alexander Litvinenko at the Intensive Care Unit of University College Hospital (Getty)

MI6’s investigation into his death was led by Christopher Steele, the ex-spy behind a dossier of compromising allegations on Donald Trump. The Independent understands investigators may consult Mr Steele in connection with the current investigation.

Counter-terror police are helping with the investigation, although the incident itself is not terror-related.

“We are speaking to witnesses, we are taking forensic samples at the scene, we are doing toxicology work,” said Mark Rowley, the outgoing head of national counter-terrorism policing.

“That will help us get to an answer, I can't say any more at this stage.”

Wiltshire Police said that Public Health England "reiterated that, based on the evidence to date, there is no known risk to the public's health.

“However, as a precaution they have advised that if you feel ill contact NHS on 111. If you feel your own or another's health is significantly deteriorating, ring 999”.

A major incident was declared at Salisbury District Hospital after the patients arrived, with people told not to attend A&E unless it is “extremely urgent”.

In Russia, Kremlin spokesman Dmitry Peskov told a conference call with reporters Russia that the government did not "have any information" but was ready to cooperate with Britain if asked.

The Kremlin has been implicated in several murders carried out on British soil, with Bulgarian writer Georgi Markov infamously murdered using a poisoned pellet fired from an umbrella on Waterloo Bridge in 1978.

A public inquiry named Russians Andrei Lugovoi and Dmitri Kovtun as the prime suspects for poisoning Mr Litvinenko at a Mayfair hotel in 2006 but attempts to extradite them from Russia failed.

In a statement dictated from his deathbed, Mr Litvinenko accused Vladimir Putin of ordering his death and a UK inquiry concluded that the Russian president had most likely approved the murder after years of “antagonism”.

“Taking full account of all the evidence and analysis available to me I find that the FSB operation to kill Litvinenko was probably approved by Mr Patrushev and also by President Putin,” Sir Robert Owen wrote in 2016.

“In the years prior to Litvinenko's death the Russian state may have been involved in the assassination of Mr Putin's critics.“

Officials in Moscow have always denied involvement in Mr Litvinenko’s death, with officials previously claiming he was involved in an illicit trade in polonium and poisoned himself.

There are believed to be concerns in the Kremlin that Russian dissidents living abroad could help Western security services probing its alleged interference in foreign elections.

Mr Litvinenko’s widow said the incident felt "like deja-vu" and called for the British Government to ensure people receiving political asylum are protected.

Marina Litvinenko told the told the BBC's World Tonight: "The state which is providing this asylum needs to be more serious, particularly now, after what has happened to Sergei...but it just shows how we need to take it seriously, all of these people asking for security and for safety in the UK."

Additional reporting by agencies