Britain has accused Russia of trying to kill former spy Sergei Skripal and his daughter with a deadly nerve agent — but the Kremlin is fighting back.

The UK blamed Russia partly on the grounds that Novichok, the poison used in the attack, was developed in the former Soviet Union. Allies including the US, France, and Germany have agreed that this is the only plausible explanation.

Regardless, the Kremlin has denied all involvement. Instead Russian officials and state media outlets have promoted numerous alternative theories which they claim could lead to the real culprits.

British Foreign Secretary Boris Johnson has described the proliferation of theories as "a classic Russia strategy of trying to conceal the needle of truth in a haystack of lies and obfuscation."

Scroll down to read the theories in question.