Who poisoned ex-Russian agent Sergei Skripal and his daughter?

British officials say a 'very rare' nerve agent used to poison former Russian spy and his daughter.

A "very rare" nerve agent". That is what the UK's interior minister says was used to poison a former Russian spy and his daughter.

Sergei Skripal and his daughter Yulia were found unconscious on a park bench in the British city of Salisbury on Sunday.

It follows several other mysterious deaths of Russians in the UK over the past few years.

Some had defected to Britain and had made allegations against President Vladimir Putin or his country's security services.

Those accusations often involved political assassinations, killings of civilians in bombings and running multi-million-dollar corruption rackets.