The leaders of France, Germany, the US and UK have issued a statement on the nerve agent attack in the UK, saying there is “no plausible alternative explanation” than Russian culpability.
They condemned the “first offensive use of a nerve agent in Europe since the Second World War”, calling it an assault on UK sovereignty.
The UK has expelled 23 Russian diplomats in the wake of the incident.
PM Theresa May on Thursday visited the site of the attack in Wiltshire.
“We do hold Russia culpable for this brazen, brazen act and despicable act,” she said.
Russia has denied any involvement in the attack. It has vowed a swift response to the expulsion of its diplomats.