"He is no longer in a critical condition", Lorna Wilkinson, director of nursing at Salisbury District Hospital in southwest England, said in a statement.
It was unclear if Williamson was referring to the attack on the Skripals or a new attack. "Charlie [Rowley] is still very unwell and will continue to require specialist, round-the-clock care".
"At this stage, we can not say with certainty that both the incident in March and this latest incident are linked".
"However, if there is anyone who saw them or met with them who we haven't already spoken to, I would urge them to contact police on 0800 789 321".
Central to the investigation are John Baker House, the supported-living accommodation where Ms Sturgess lived, Mr Rowley's home in Amesbury, and Salisbury's Queen Elizabeth Gardens, which remains cordoned off.
Croatia to Wear Red & White Checkers in World Cup Final
Here we take a look at the four most underrated players of the tournament. Croatia must recover quickly for Sunday's showpiece - no easy feat.
London, Jul 11 Britain's top counterterrorism police officer Neil Basu says the nerve agent Novichok could remain active for 50 years if kept in a sealed container.
It is believed that Mr Rowley, 45, touched a vessel that contained the deadly substance following the attempted assassination of Sergei and Yulia Skripal earlier this year.
"I simply cannot offer a guarantee" regarding public safety, said the head of anti-terrorism Neil Basu during a press briefing in London, before calling on the population not to pick up objects such as syringes or unusual containers ". We sincerely apologise if any offence was caused, especially to the families of Dawn Sturgess and Charlie Rowley, and understand the timing of the release of this product may have lacked sensitivity.
"This is a very rare substance banned by the global community and for there to be two separate, distinct incidents in one small English county is implausible to say the least", he said.
An extra £5m of government funding has been handed out to help the Wiltshire economy recover after a couple were poisoned by a nerve agent.
How badly affected people are varies greatly - for example, some people are able to break down the chemicals three times as fast as others.
"If it's in an enclosed container it takes a long time before it becomes inactive".