Experts in chemical, biological, radiological and nuclear (CBRN) emergencies are conducting a search at the British property where exiled Russian oligarch Boris Berezovsky was found dead, police said on Sunday.
"Specially trained officers are currently at the scene, including CBRN trained officers, who are conducting a number of searches as a precaution," Thames Valley Police said in a statement.
British police opened an investigation after Berezovsky's body had been found by one of his bodyguards in a bathtub at his property in Ascot, Berkshire, on Saturday.
The area around the property has been cordoned off to allow the investigation to take place.
"I would like to reassure residents that we are confident there is no risk to the wider community," Superintendent Stuart Greenfield said.
Police is treating Berezovsky's death as "unexplained" for now, although some of his family friends and close associates earlier claimed he had suffered a heart attack.