The health of Yulia Skripal, the daughter of former Russian spy Sergei Skripal, is rapidly improving and she is no longer in a critical condition.
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 medical state has been described as stable, while her father is still critical.
Police say they now believe Skripal and Yulia were poisoned with a nerve toxin left on the front door of their home in the English city of Salisbury.
On Thursday, officers had cordoned off a children's play area near the Skripals' home "as a precautionary measure," according to statement from the force.
Meanwhile, Russia claims Britain is breaking international law by not providing them with information on Yulia Skripal.
"We witness the hindrance for Russian representatives accessing injured Russian citizens. So the UK openly, without any constraint, violates the norms of international law," said Foreign Ministry spokeswoman, Maria Zakharova.
Yulia and her father were found slumped on a bench outside a shopping centre in Salisbury in March.
Britain has blamed the attempted murder on Russia, while Moscow has accused London of framing Russia to stoke anti-Russian hysteria.
The countries have mutually expelled diplomats in the wake of the poisoning, as have dozens of Britain's Western allies.