England’s Prime Minister Theresa May says a former Russian spy and his daughter were poisoned by a military‑grade nerve agent of a type developed by Russia.
Nerve agents are chemical poisons which change the way the nerves work in the human body.
They stop messages from the brain from getting sent to the muscles and organs.
The British Prime Minister told the UK House of Commons that the government had concluded it was "highly likely" that Russia was responsible for the attack on Sergei Skripal and his daughter Yulia in Salisbury last Monday.
She said Russia's ambassador in London has been summoned to explain whether it was "a direct action by the Russian state" or the result of it "losing control" of its stock of nerve agents.
The BBC reports that the chemical used in the attack has been identified as being part of a group of nerve agents known as "Novichok".
May said Russia must "immediately provide full and complete disclosure" of the Novichok programme to the Organisation for the Prohibition of Chemical Weapons.
