Police have said they know what nerve agent used in the attack but have declined to name it or how they suspect it was administered.
Mr Skripal and Yulia, 33, are still in a "very serious" condition five days after they were discovered slumped on a bench in the city centre.
"You can not tolerate a government assassination on British soil - it is absolutely beyond the pale and needs a reaction", he said.
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.
DS Bailey is among 21 people who received medical treatment following exposure to the nerve agent.
Irina Petrova, a friend of the former double agent's daughter, said Yulia was a "normal kind of person" who had lived in the United Kingdom for five years after her father's return to Britain in a spy swap.
Authorities are racing to determine the source of the nerve agent used against Skripal, who came to Britain in 2010 as part of a spy swap. "He did his very best on that night".
"The Government will not be acting precipitously in response to what has happened". Some called for investigations to be re-opened into the deaths of Russian exiles in Britain in recent years.
Kleymenov said that they will not be safe, and advised those who have betrayed the Russian motherland not to choose Britain as a safe place to live, as too many "strange" incidents have occurred in recent years that had unsafe outcomes. He also said at the time that he provided information about GRU agents in Europe, receiving over $100,000 in return.
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We are committed to doing all we can to bring the perpetrators to justice - whoever they are, and wherever they may be.
Skripal betrayed dozens of Russian agents to British intelligence before his arrest in 2004. In 2010, he was released from prison and sent to Britain as part of a spy exchange with Western agencies.
A British public inquiry said Litvinenko's murder had probably been approved by Putin and carried out by two Russians, Dmitry Kovtun and Andrei Lugovoy.
Meanwhile Salisbury's MP John Glen, also a Government minister, attempted to reassure his constituents that a "whole range of tools are at our disposal" once it is established who was behind the incident.
Government minister John Glen, the member of parliament for Salisbury, said a "whole range of tools are at our disposal" once it is established who was behind the incident.
She said 240 witnesses had been identified and 250 officers from eight out of 11 of the country's counter-terrorism units were handling the case with "speed and professionalism".
In Russia, some media took an nearly jocular tone. The cause is unclear: Some reports say he died in a auto accident while on holiday in Russian Federation, others that he died of liver failure.
"Something's not right there, maybe it's the climate, but in the past few years there have been a lot of odd occurrences there with a awful outcome".
The presenter referred to a series of events in which people were hanged, poisoned, died in helicopter crashes and fell out of windows.