Yulia Skripal, the daughter of ex-spy Sergei Skripal, is improving rapidly and no longer in a critical condition, says the hospital treating her.
She and her father were admitted nearly four weeks ago after being exposed to a nerve agent in Salisbury.
The BBC understands from separate sources that Ms Skripal is conscious and talking. However Mr Skripal remains in a critical but stable condition, Salisbury District Hospital said.
Doctors said Ms Skripal, “has responded well to treatment but continues to receive expert clinical care 24 hours a day”.