Specialist team members in military protective suits use a jar in the front doorway as they search the fenced off John Baker House for homeless people on Rollestone Street in Salisbury, England, July 6, 2018.
Specialist team members in military protective suits use a jar in the front doorway as they search the fenced off John Baker House for homeless people on Rollestone Street in Salisbury, England, July 6, 2018.

A British man who was poisoned with a nerve agent is no longer in critical condition, an official at the London hospital that is treating the victim said Wednesday.

"Charlie Rowley is made further progress overnight," said Salisbury District Hospital nursing director Lorna Wilkinson. "His condition is now serious but stable ...," she added.

The 45-year-old Rowley and 44-year-old Dawn Sturgess, both British nationals, became sick on June 30 in the town of Amesbury after being exposed to Novichok, a military-grade nerve agent produced in the Soviet Union during the Cold War.

Sturgess died and British police have opened a murder investigation.

British Defense Secretary Gavin Williamson told parliament on Monday that Russia was responsible for Sturgess' death, a charge that Russia has denied.

Metropolitan Police Assistant Police Commissioner Neil Basu said there is no definitive proof that the Novichok that poisoned Rowley and Sturgess was the same batch used in March against former Russian spy Sergei Skripal and his daughter, Yulia.