Video report by ITV News Correspondent Sejal Karia
Hundreds of people who passed through the area where ex-Russian spy Sergei Skripal and his daughter may have been poisoned by a nerve agent have been told to wash their clothes and other items as a precaution.
Investigators found traces of the substance at both a Zizzi restaurant and the Mill pub in central Salisbury, both locations linked to the poisoning.
The authorities issued "precautionary advice" urging anyone who had been in either venue last Sunday afternoon or Monday to clean the clothes they were wearing.
Traces of the nerve agent were reportedly found on and around the table where the pair ate at Zizzi, but Scotland Yard, which is running the investigation, would neither confirm nor deny the report.
Investigators wearing hazmat suits and gas masks were also seen bagging up items inside The Mill pub.
But health authorities insisted the risk to the public was sleight.
England's chief medical officer Dame Sally Davies said she believed fewer than 500 people would have been in either venue during between Sunday and Monday, adding that none were at risk.
"I am confident this has not harmed the health of anyone who was in the Mill pub or Zizzi restaurant," she said.
But she added that as a precaution, as part of "a belt-and braces approach", anyone who was in either Zizzi or the Mill pub from 1.30pm last Sunday to evening closing on Monday "should clean the clothes they were and the possessions they handled while there".
Some questioned why the advice to wash clothes was being issued a week after the events that left Mr Skripal, 66, and his daughter, Yulia, 33, fighting for their lives.
But Dr Jenny Harries, joint director of Public Health England (PHE), defended the decision.
She told reporters at a press conference on Sunday: "This is about a very, very small risk of repetitive contact with traces of contamination that people may have taken out.
"The advice we're giving today about washing clothes - very simple things... that will remove that risk as we go forward."
Further advice is available on the Public Health England website.
During his afternoon sermon on Sunday, the Bishop of Salisbury, the Rt Revd Nicholas Holtam called the attack "a violation of our community".
Mr Skripal and his daughter remain critically ill in hospital, while a police officer, Detective Sergeant Nick Bailey, who helped them is in intensive care but conscious and speaking.
Officials have not yet confirmed exactly what the nerve agent was, and say it is still unclear exactly how and when it was administered.
Cordons remain in place at a number of locations across the city, including Mr Skripal's house and the cemetery where his wife and son are buried.
There was further police activity at the London Road cemetery on Saturday.
Officers in hazmat suits removed items and covered Mr Skirpal's son's memorial stone with a forensic tent, but Scotland Yard said no exhumations had taken place.
Specialist armed forces teams are also helping to investigate and to clear scenes feared to have been contaminated with nerve agent.
Soldiers were seen at the South Western Ambulance Service station on Saturday after a vehicle was winched on to the back of an Army low-loader and taken away.
Home Secretary Amber Rudd chaired a meeting of the government's Cobra emergencies committee on Saturday, four days after counter-terrorism police took over the investigation.
But the government has said it is still too early to say who was behind the attack.
However, with suspicion falling on Russia, MPs are calling for the UK to adopt new sanctions that would target Russian officials involved in corruption and human rights abuse.
Conservative MPs are in discussions about adopting a British version of the US Magnitsky Act which imposes travel bans and asset freezes on named individuals linked to abuse.
Foreign Secretary Boris Johnson and Ms Rudd have agreed to introduce such legislation in the UK, The Sunday Telegraph reported.
The Kremlin has firmly denied any connection to the poisoning.