Pair won't survive

Doctors in Britain who treated former Russian spy Sergei Skripal and his daughter following their March poisoning in Salisbury have said they initially feared the pair would not recover.

Skripal and his daughter Yulia, who was visiting from Moscow, collapsed on March 4 on a bench in the city in southwestern England where the former double agent lived.

London blamed Moscow for using a Soviet-made nerve agent known as novichok on the pair, which Moscow has furiously denied, sparking a diplomatic crisis between Russia and Britain.

Stephen Jukes, the intensive care consultant at Salisbury District Hospital, who treated them a week after their admission, said in a BBC interview that once the nerve agent was detected "all the evidence was there that they would not survive".

Jukes revealed the hospital's medical team first suspected the Skripals were suffering from an opioid overdose, but that the diagnosis soon changed to a nerve agent poisoning.

The doctors interviewed said that all the initial focus was on simply keeping the pair alive.

The pair were heavily sedated and given large doses of drugs designed to protect them from the effects of the poison and help re-start their bodies' natural production of a key enzyme.