Britain says will respond robustly if Russia behind ex-spy's illness

Britain will respond robustly if it is proved that Russia was involved in an incident which left a former Russian double agent in a critical condition, Foreign Secretary Boris Johnson said on Tuesday.

"There is much speculation about the disturbing incident in Salisbury, where a 66-year-old man, Sergei Skripal, and his 33-year-old daughter, Yulia, were found unconscious," Johnson told parliament.

"While it would be wrong to pre-judge the investigation, I can reassure the House that should evidence emerge that implies state responsibility, then her majesty's government will respond appropriately and robustly."