Inspectors from the Organisation for the Prohibition of Chemical Weapons (OPCW) have begun work at the scene of the nerve agent attack on former Russian agent Sergei Skripal in the English city of Salisbury, a Reuters photographer said.
The inspectors were seen arriving at the Mill pub in Salisbury where Skripal and his daughter Yulia had a drink on March 4.
The pair were later found unconscious on a bench outside The Maltings shopping centre. They remain critically ill in hospital.
More victims likely if chemical weapons used: Moscow
Moscow rejected British claims the chemical weapon "Novichok" was used in the poisoning of an ex-spy in England, saying a nerve agent would have killed people on the spot.
"Any use of a military-grade poison would inevitably lead to numerous casualties immediately on the site of the poisoning," Vladimir Yermakov, head of the Russian foreign ministry's non-proliferation and arms control department, told foreign diplomatic staff.
"But the picture in Salisbury is completely different," he added.
