A murder investigation was launched today following the death of a British woman after being exposed to a nerve agent close to a city where a former Russian spy and his daughter were poisoned with the same deadly chemical four months ago.
Dawn Sturgess, 44, died at Salisbury District Hospital in Wiltshire yesterday after falling ill on June 30.
Her partner Charlie Rowley, 45, who also fell ill after being exposed to the nerve agent, remains in a critical condition in hospital.
Scotland Yard said they have launched a murder investigation - the second major probe involving the military-grade nerve agent this year, following the case of Sergei Skripal and his daughter in March.
Tests have revealed that the Amesbury couple were exposed to Novichok, a nerve agent developed by the Soviet military during the Cold War in what is the first known offensive use of such a chemical weapon on European soil since World War II.
Security services believe the couple were inadvertently exposed to the same nerve agent used to attack Skripal and his daughter four months ago.
"This is shocking and tragic news. Dawn leaves behind her family, including three children, and our thoughts and prayers are with them at this extremely difficult time," assistant commissioner Neil Basu, head of UK counter-terrorism policing, said,
"This terrible news has only served to strengthen our resolve to identify and bring to justice the person or persons responsible for what I can only describe as an outrageous, reckless and barbaric act," he said.
"Police and security officials are working urgently to establish the facts of this incident, which is now being investigated as a murder. The government is committed to providing full support to the local community as it deals with this tragedy," she said.
The UK home secretary Sajid Javid had demanded an explanation from Russian authorities last week over how the deadly Soviet era poison ended up poisoning former Russian spy Sergei Skripal and his daughter Yulia in March and then the British couple more recently.
However, Russian authorities have repeatedly denied any involvement.
After the hospitalisation of Sturgess and Rowley, Javid accused the Russian state of using Britain as a "dumping ground for poison".
"This desperately sad news only strengthens our resolve to find out exactly what has happened," he said following the news of Sturgess' death in hospital overnight.
The Russian Embassy hit back, accusing the government of trying to "muddy the waters" and "frighten its own citizens".
In a statement, the Met Police has said that the possibility the poisoning of the Skripals and Sturgess and Rowley are linked is a "clear line of inquiry".
Following the death, there are growing fears of a wider risk to public health in the region but Public Health England stressed the risk to the general public "remains low".
"Wash your clothes in a washing machine and to keep your items double-bagged and securely fastened, if they are dry-clean only," he said.