Chemical security

Russian spy: What are Novichok agents and what do they do?

A former Russian spy and his daughter were poisoned by a chemical that is part of a group of nerve agents known as Novichok, UK Prime Minister Theresa May has said.

Sergei Skripal and his daughter Yulia remain critically ill after the attempted murder in Salisbury on 4 March.

The chemical was identified by experts at the defence and science laboratory at Porton Down.

So what do we know about this group of military-grade nerve agents?

1) They were developed in the Soviet Union

The name Novichok means "newcomer" in Russian, and applies to a group of advanced nerve agents developed by the Soviet Union in the 1970s and 1980s.

They were known as fourth-generation chemical weapons and were developed under a Soviet programme codenamed "Foliant".

In 1999, defence officials from the US travelled to Uzbekistan to help dismantle and decontaminate one of the former Soviet Union's largest chemical weapons testing facilities.

According to a senior defector, the Soviets used the plant to produce and test small batches of Novichok. These nerve agents were designed to escape detection by international inspectors.