*London: *British police requested military assistance in investigating a nerve agent attack on a former Russian double agent as speculation mounted Friday about how London could respond if a state actor were to blame.
Police extended the cordon around the modest suburban home of Sergei Skripal in Salisbury, the quiet city in southwestern England where he and his daughter Yulia were found slumped on a bench on Sunday.
The pair remain unconscious in a critical but stable condition, while Nick Bailey, one of the first police officers on the scene, is now sitting up and talking after initially being admitted to intensive care.
With police also hurt in the attack, pressure is intensifying on Prime Minister Theresa May to find and punish the culprits.
The involvement of "a British citizen, especially a policeman, requires the immediate and strong involvement of the British authorities," Chatham House analyst Mathieu Boulegue told AFP.
Around 21 people have been treated, according to Kier Pritchard, chief constable for Wiltshire Police.
"A number of those have been through the hospital treatment process, they're having blood tests, they're having treatment in terms of support and advice," he added.
Authorities are racing to find the source of the nerve agent used against 66-year-old Skripal, who came to Britain in 2010 as part of a spy swap, as politicians warned it bore the hallmarks of an attack by Russia.
National counter-terrorism police, who are leading the investigation, announced on Friday that they had requested assistance from the military "to remove a number of vehicles and objects from the scene".
"Military assistance will continue as necessary during this investigation," they added, with media reporting that more than 100 personnel may be involved.
During a visit to the site on Friday, interior minister Amber Rudd called the attack "outrageous" but urged people to "give the police the space they need to really go through the area carefully, to do their investigation". APP/AFP