LONDON: British Prime Minister Theresa May will chair a meeting of her national security team today after weekend confirmation that traces of a nerve agent used in the attempted murder of a Russian former double agent were found in a pub and a restaurant he visited.
May and senior ministers will receive an update on the investigation into the March 4 attack on Sergei Skripal, 66, and his 33-year-old daughter Yulia, as pressure mounts in Britain for answers over the incident.
The Times reported that the prime minister is on the brink of publicly declaring Russia's involvement, possibly following the national security council meeting.
She is considering a raft of "hard line" responses, with diplomatic expulsions and rescinding the visas of Kremlin-linked residents among the possible measures, the paper said.
The Russian pair were found slumped on a bench in Salisbury, southwest England, and remain in a critical but stable condition in hospital.
Authorities have yet to confirm the precise substance involved in the attack.
Sally Davies, England's chief medical officer, revealed Sunday that up to 500 people who may have come into minimal contact with the nerve agent should wash their clothes and belongings as a precaution.
The advice was aimed at locals who visited The Mill pub and Zizzi's restaurant that the targeted duo visited prior to falling ill.
"There has been some trace contamination by the nerve agent," Davies said.
"I am confident this has not harmed the health of anyone who was in The Mill pub or Zizzi's." The BBC reported a table at the restaurant was so contaminated that it had to be destroyed.
Davies added that pub and restaurant-goers last Sunday or Monday should wash clothing in the washing machine, while dry clean-only clothes should be put inside two tied plastic bags and safely stored while awaiting further advice.
She also gave detailed instructions for cleaning items such as mobile phones, handbags, jewellery and eyeglasses.
The advice, given a week after the incident, surprised residents repeatedly reassured they were in no danger Steve Cooper, who was in the pub around the same time as Skripal, told the BBC he was "concerned".
The risk to public health remained low and the advice was precautionary, Public Health England said.
"It is possible, but unlikely, that any of the substance which has come into contact with clothing or belongings could still be present in minute amounts," PHE said in a statement.
"Over time, repeated skin contact with contaminated items may pose a small risk to health." Nick Bailey, one of the first police officers on the scene after Skripal and his daughter fell ill, is in hospital but conscious, local police have said.
Alastair Hay, an environmental toxicology professor at Leeds University, said the advice on cleaning clothes and possessions would provide an "extra guarantee of safety".
"If no one has had physical symptoms suggestive of nerve agent contact by now it is unlikely that they are a risk," he said.
"Nerve agents vary in their rate of environmental breakdown. Sarin is one of those that degrades more rapidly whereas VX is more persistent." Meanwhile, Britain's armed forces are expected to continue assisting police in the probe today.
Around 180 troops, including chemical warfare experts, have been deployed in Salisbury after investigators requested expert assistance.
Interior Minister Amber Rudd has said police were examining more than 200 pieces of evidence, had identified more than 240 witnesses, and were ploughing through security camera footage.
The Telegraph reported that experts were testing the substance to ascertain if it was produced in Russia.