Theresa May is on the verge of publicly blaming Russia for the attempted murder of Sergei and Yulia Skripal and ordering expulsions and sanctions against President Putin’s regime.

An announcement could come as early as today after a meeting of the government’s National Security Council at which ministers will be presented with the latest intelligence on the Salisbury attack.

Senior government sources suggested that the police and security services had established sufficient evidence to link Moscow with the nerve agent used to try to kill the former Russian double agent and his 33-year-old daughter. One said that ministers were preparing to take a “hard line on early action”.