LONDON • The doctors who treated a Russian former spy and his daughter after they were poisoned with a nerve agent in Britain say they do not know what the pair's long-term health outlook is - and initially feared the incident could have been much worse.

Mr Sergei Skripal, a former colonel in Russia's military intelligence who betrayed dozens of agents to Britain, and his daughter Yulia were found unconscious on a public bench in the southern English city of Salisbury on March 4.

Staff at Salisbury hospital, where they were treated, told the BBC on Monday night that some had started to wonder whether they too would fall victim to the nerve agent.

Asked about the long-term impact of the poisoning on the Skripals' health, the hospital's medical director, Dr Christine Blanshard, said the prognosis was uncertain.

"The honest answer is we don't know," she said, according to extracts of an interview released by the BBC's Newsnight programme.

Britain has said it is highly likely that Russia was responsible for the poisoning of the Skripals, and Western governments, including the United States, have expelled more than 100 Russian diplomats. Russia has denied any involvement in the poisoning and retaliated in kind.

Ms Yulia Skripal said last week that her recovery had been "slow and extremely painful" and that she was lucky to have survived.

Hospital staff too said they had expected the Skripals would die as a result of the poisoning.

"All the evidence was there that they would not survive," said Dr Stephen Jukes, an intensive care consultant who had treated the Skripals.

REUTERS