Ex-spy’s illness stirs U.K. to warn of action against Russia

Britain will respond “appropriately and robustly’’ if Russia’s involvement is established in the case of an ex-Russian spy who became critically ill after coming into contact with an “unknown substance’’ in southern England, the U.K. foreign secretary said Tuesday.

Boris Johnson told lawmakers in the House of Commons that he wasn’t “pointing fingers’’ as to who might be responsible for the collapse of Sergei Skripal, who was found slumped on a bench together with his daughter Yulia on Sunday. But he stressed that if state involvement was proven, Britain would take action.

“I say to governments around the world that no attempt to take innocent life on U.K. soil will go either unsanctioned or unpunished,’’ he said.

Johnson said the crisis could affect British participation at the soccer World Cup in Russia this summer. He said that if Russian involvement is proved, “it will be very difficult to imagine that U.K. representation at that event will go ahead in the normal way.’’

The Foreign Office clarified that the comment referred to dignitaries and officials, not the England team, which is scheduled to compete at the tournament.

British counterterror specialists took over the investigation from local authorities as they sought to unravel the mystery of why Skripal and his daughter collapsed in Salisbury, 90 miles (145 kilometres) southwest of London.