London: Yulia Skripal, who was found poisoned on a park bench in a small English city this month along with her father, former Russian spy Sergei Skripal, is showing improvement and is no longer in critical condition, the hospital that is treating her said.

British authorities have blamed Russia for the poisoning, which they say was carried out with a deadly nerve agent developed by Soviet scientists and known as a Novichok.

"I'm pleased to be able to report an improvement in the condition of Yulia Skripal," Dr Christine Blanshard, medical director for Salisbury District Hospital, said in a statement. "She has responded well to treatment but continues to receive expert clinical care 24 hours a day."

Her father remained in critical but stable condition, the hospital said in a statement. Sergeant Nick Bailey, an emergency medical worker who was also exposed to the nerve agent, was released from the hospital a week ago; there was no further word on his condition.

The announcements came a day after British authorities said that Yulia and her father, a former colonel for Russian military intelligence who was widely believed to have been a double agent, had been poisoned after the nerve agent was applied to the front door of their house, resolving one of the many mysteries in the case.