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

The 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 Novichok.

“I’m pleased to be able to report an improvement in the condition of Yulia Skripal,” Dr. Christine Blanshard, the 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.”

Ms. Skripal’s father remains in critical but stable condition, the hospital said in a statement. Det. Sgt. Nick Bailey, a policeman who was also exposed to the nerve agent, was released from the hospital a week ago; there was no further word on his condition.