Russia has expelled 60 US diplomats and announced it would eject scores from other countries that have joined London and Washington in censuring Moscow over the poisoning of a double agent in England.

The US ambassador also ordered the closure of the consulate in St Petersburg, in retaliation for the biggest expulsion of diplomats since the Cold War.

The tit-for-tat expulsions have come after Britain blamed Russia for the nerve-agent poisoning of Russian double agent Sergei Skripal and his daughter Yulia in the English city of Salisbury earlier this month.

Moscow had denied any involvement in the poisoning.

Russian President Vladimir Putin, facing a stuttering economy and an unusual show of Western unity that has included even states traditionally friendly towards Moscow, appeared to have stuck to the diplomatic playbook with the symmetrical response.

US ambassador John Hunstman was summoned to the Russian foreign ministry on Thursday and told that 60 diplomats from US missions had a week to leave Russia, as Washington had expelled 60 Russians.

At a meeting with Deputy Foreign Minister Sergei Ryabkov, Mr Huntsman was also told that the US consulate in St Petersburg would be closed, mirroring the the US closure of Russia’s consulate in the US city of Seattle.

“As for the other countries, everything will also be symmetrical in terms of the number of people from their diplomatic missions who will be leaving Russia, and for now that’s pretty much it,” said Foreign Minister Sergei Lavrov.

That approach will mean that, among other countries affected, Australia will see two diplomats sent home, France, Germany and Poland would each have four of their diplomats in Moscow sent home, Ukraine would forfeit 13 diplomats, and Denmark, Albania and Spain would each have two of their embassy staff expelled.

Russia has already retaliated in kind after Britain initially expelled 23 diplomats.

Agent’s daughter significantly improved

Meanwhile, Mr Skripal’s daughter Yulia is no longer in a critical condition and improving rapidly, according to the hospital treating her, Reuters has reported.

Yulia, 33, and her father were found on March 4 slumped on a bench in their home town of Salisbury, retching and frothing at the mouth after having been contaminated by the suspected nerve agent.

The Skripals may still suffer brain damage as a result of the attack. Photo: Facebook

British counter-terrorism police believe a nerve toxin had been left on the front door of his home.

Last week, a British judge said the Skripals might have suffered permanent brain damage as a result of the attack.

“I’m pleased to be able to report an improvement in the condition of Yulia Skripal,” 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 father remained in a critical but stable condition, the hospital said.