The former Russian spy poisoned with a nerve agent is no longer critically ill in hospital, according to doctors.

Sergei Skripal, 66, is “responding well to treatment, improving rapidly and no longer in a critical condition”.

It comes on the back of the news his daughter Yulia’s condition is also improving after the attack on 4 March, which left them both fighting for their lives. 

Police believe Skripal and his daughter, who was visiting him from Russia, first came into contact with the Novichok agent at his home in Salisbury, Wiltshire.

Dr Christine Blanshard, medical director at Salisbury District Hospital, said: “Following intense media coverage yesterday, I would like to take the opportunity to update you on the condition of the two remaining patients being treated at Salisbury District Hospital.

“Last Thursday, I informed you that Yulia Skripal’s condition had improved to stable. As Yulia herself says, her strength is growing daily and she can look forward to the day when she is well enough to leave the hospital.

“Any speculation on when that date will be is just that – speculation. In the meantime, Yulia has asked for privacy while she continues to get better – something I’d like to urge the media to respect.

“I also want to update you on the condition of her father, Sergei Skripal. He is responding well to treatment, improving rapidly and is no longer in a critical condition.

“As you’ll appreciate, I won’t be giving any further updates at this time.”

Following the news that Skripal’s condition had improved, the Russian Embassy to the UK tweeted: “Good news!” 

In her first statement since coming out of a coma last week, Yulia, 33, said: “I woke up over a week ago now and am glad to say my strength is growing daily. I am grateful for the interest in me and for the many messages of goodwill that I have received.”

Russia has appealed for the UK to issue visas for relatives to visit the Skripals in hospital in Salisbury, where they are being treated for exposure to the deadly chemical.

On Friday the Home Office announced it has refused to grant Yulia’s cousin, Viktoria Skripal, a visa to visit Britain. 

A Home Office spokesman said: “We have refused a visitor visa application from Viktoria Skripal on the grounds that her application did not comply with the Immigration Rules.”

Russian earlier warned Britain is “playing with fire and will be sorry” over the poisonings as the two countries traded jibes at the United Nations.

Russian UN ambassador Vasily Nebenzya claimed the UK’s main argument about the “unquestionable Russian origin” of the Novichok is “no longer valid” following comments from Porton Down’s Gary Aitkenhead.

Moscow called the UN Security Council meeting to discuss the incident, with foreign minister Sergey Lavrov saying the UK has “legitimate questions” to answer about what happened.

But security minister Ben Wallace said it was “beyond reasonable doubt” that Russia was to blame for the attack, as the UK sought to maintain diplomatic pressure over the incident.

On Wednesday, Russia lost a vote at the Organisation for the Prohibition of Chemical Weapons (OPCW) in The Hague on its demand for its experts to be involved in testing samples of the substance used in the Salisbury attack.

Meanwhile, two guinea pigs were found dead at Mr Skripal’s home after the property was sealed off for investigations.

The Department for Environment, Food and Rural Affairs added a cat was also found in a distressed state at the house and a decision was taken to euthanise the pet.

Meanwhile, the Trump administration on Friday announced new economic sanctions on seven Russian oligarchs and 17 top government officials.

The sanctions against 24 allies of Russian President Vladimir Putin is one of Washington’s most aggressive moves to punish Moscow for what it called a range of “malign activity,” including alleged meddling in the 2016 US election.

The action freezes the US assets of “oligarchs” such as aluminum tycoon Oleg Deripaska, a close associate of Putin, and lawmaker Suleiman Kerimov, whose family controls Russia’s largest gold producer, Polyus.

The sanctions are largely a reply to what US intelligence agencies say was Russian interference in the presidential election, although the Treasury Department said it was as a response to a series of adversarial actions by Moscow.

As well as freezing the assets of the officials and the companies they own or control, the sanctions also prevent Americans from doing business with them.

The sanctions could hurt the Russian economy, especially the aluminum, financial and energy sectors.

In announcing the sanctions, Treasury Secretary Steve Mnuchin said: “The Russian government operates for the disproportionate benefit of oligarchs and government elites.”

He said Moscow “engages in a range of malign activity around the globe, including continuing to occupy Crimea and instigate violence in eastern Ukraine, supplying the Assad regime with material and weaponry as they bomb their own civilians, attempting to subvert Western democracies, and malicious cyber activities.”