Sergei and Yulia Skripal were treated in hospital after becoming seriously ill through contact with the nerve agent novichok

The British authorities today rejected a claim by the Russian niece of Sergei Skripal, who was poisoned with nerve agent in Salisbury, that he was dead.

Viktoria Skripal, 46, is widely seen as being used as an instrument by the Russian government to put pressure on the British authorities over the attack, which Theresa May has blamed on Moscow.

Ms Skripal said today that she suspects her uncle, a former double agent, could be dead because he has not been photographed since he was poisoned, or made contact with his family in Russia.

Security sources said that Mr Skripal, who spent two months in hospital after he was attacked with novichok in March, was not dead. In the event of his death it would be