Yulia Skripal is no longer in a critical condition and is “improving rapidly” following a nerve agent attack in Salisbury.
Doctors said her father, Sergei Skripal, remains in a critical but stable condition as the global impact of the attempted assassination continues to widen.
Dr Christine Blanshard, the medical director for Salisbury District Hospital, said: “I’m pleased to be able to report an improvement in the condition of Ms Skripal.
“She has responded well to treatment but continues to receive expert clinical care 24 hours a day.
“I want to take this opportunity to once again thank the staff of Salisbury District Hospital for delivering such high quality care to these patients over the last few weeks.
“I am very proud both of our front-line staff and all those who support them.”
The news came a day after police announced that the novichok used to poison Ms Skripal and her father is likely to have been placed on the front door of his home.
Deputy Assistant Commissioner Dean Haydon, the senior national coordinator for counter-terrorism policing, said: “At this point in our investigation, we believe the Skripals first came into contact with the nerve agent from their front door. We are therefore focusing much of our efforts in and around their address.”
Detective Sergeant Nick Bailey, who was among the first officers to visit the house in Salisbury, also fell severely ill but has since been discharged from hospital.
A total of 38 people were treated for varying symptoms resulting from exposure, including an unnamed hospital outpatient, which could have resulted from exposure to the nerve agent either by contact with the Skripals or items they touched.
A court hearing last week was told that Mr Skripal and his daughter may have suffered life-long brain damage as a result of the attack.
Speaking last week, Mr Justice Williams told the Court of Protection: “The precise effect of their exposure on their long term health remains unclear, albeit medical tests indicate that their mental capacity might be compromised to an unknown and so far unascertained degree.”
At the time, a consultant treating the victims in intensive care said that Mr Skripal was unable to communicate in any way, but said his daughter was unable to communicate in any “meaningful way”.
The doctor said it was not yet possible to tell whether the pair can recover fully.
The hearing was held to allow doctors to pass fresh blood samples from the victims and medical records to the Organisation for the Prohibition of Chemical Weapons (OPCW) to aid an ongoing international investigation.
The samples will be used to identify the nerve agent used to poison the pair and for DNA analysis confirming the origin of blood originally tested by the British military.
Experts at the Defence, Science and Technology Laboratory at Porton Down identified the nerve agent used against the Skripals as part of the Soviet-developed “novichoks” group.
Traces have been found at various sites visited by the pair in Salisbury, investigators said, but at “lower concentrations to that found at the home address”.
The Prime Minister said Russia had provided “no credible explanation” on how the substance came to be used on the streets of Wiltshire and accused Vladimir Putin’s government of culpability.
Russia has denied involvement and accused the UK of violating international law by refusing to provide information it requested.
Britain expelled 23 Russian diplomats, who were described as “undeclared intelligence officers”, sparking the expulsion of 23 British diplomats by the Kremlin.
Pressure has since been mounting on Russia as the EU, US and other allies have made statements of solidarity with the UK and moved to expel diplomats themselves.
Ms Skripal was visiting her father on a holiday from Russia when they fell ill after going for lunch in Salisbury on 4 March, with passers-by trying to help after finding the pair slumped on a bench.
Witnesses described them twitching, vomiting and stopping breathing – all symptoms consistent with nerve agent exposure.
The deadly chemicals attack the nervous system and can kill victims by paralysing the respiratory system, causing oxygen deprivation and eventual suffocation.
Mr Skripal moved to the cathedral city after being handed over in a Cold War-style spy swap in 2010.
He was jailed for treason in Russia for allegedly passing secrets to MI6 while a colonel in the GRU military intelligence agency.
Mr Skripal’s wife died in 2012, his son passed away last year and he is also believed to have lost his brother in recent years.
The Metropolitan Police has said the criminal investigation is likely to take “many months” and continues to appeal for anyone with information to come forward.