Both are under treatment in hospital but in stable condition.
Former Russian military intelligence (GRU) Colonel Sergei Skripal continued to provide information to western intelligence agencies after arriving in the United Kingdom in 2010, the Financial Times daily said on Friday citing security officials.
The personnel includes the Royal Marines and military personnel who have specialist training in chemical warfare and decontamination, .
Britain's Ministry of Defense and the police said some 180 troops, including some chemical experts, have been sent to Salisbury to remove ambulances and other vehicles involved in the incident as well as other objects.
Sergei and Yulia Skripal were found unconcious on a bench in Salisbury on Sunday, and are now fighting for their lives in a local hospital.
Police thanked well-wishers for their support for the officer, while the force's temporary chief constable Kier Pritchard said: "I have just left the bedside of our officer and family in hospital".
The UK is preparing retaliatory measures if it's shown that Russian Federation was responsible for the attack on Skripal who had settled in Salisbury, southern England after a spy swap in 2010.
Assistant commissioner Mark Rowley, head of counter terrorism policing at the Metropolitan Police, says scientists have identified the substance used.
A police officer who helped investigate was in serious condition, and a total of 21 people have received medical treatment.
The use of a nerve agent - with its last known use in a targeted attack against the Kim Jong-nam, the estranged brother of North Korea's leader - and Mr Skripal's past have suggested that the Russian state was involved in the attack.
On Thursday night, an eyewitness said police had been searching a auto at a vehicle recovery centre close to the Russian victim's home earlier that day.
Police have cordoned off sites, including the cemetery where Sergei Skripal's wife is buried. Health officials insist there has only been a low risk to the public.
They are former Sergei Skripal, his daughter Yulia and police Sgt. Nick Bailey.
"This was attempted murder in the most cruel and public way", said Rudd, Britain's top police official.
Police say their deaths are part of the investigation into the poisoning of Mr Skripal and his daughter Yulia, who were found slumped on a park bench in Salisbury on Sunday evening. He is now able to talk though his condition remains serious, interior minister Amber Rudd said on Thursday.
"I can reassure the House that, should evidence emerge that implies state responsibility, then Her Majesty's government will respond appropriately and robustly", Johnson said on Tuesday in an urgent question session at the House of Commons.
The minister called the accusations of Moscow's involvement in the attack on the former secret service agent unfounded.
Rudd says the attack is an "outrageous crime" and a "brazen and reckless act" but cautions it is too early to say who was behind it.
Per the Independent, Skripal "was given refuge in Britain after being exchanged in 2010 for Russian agents caught in the West as part of a Cold War-style swap in Vienna".
While she said speculation must be avoided, she said "people are right to want to know who to hold to account".
The attack has been likened in Britain to the assassination of ex-KGB agent Alexander Litvinenko, a critic of Russian President Vladimir Putin, who died in London in 2006 after drinking green tea laced with radioactive polonium-210.
Skripal has been living in Britain since 2010, when he was part of a prisoner exchange for 10 Russian spies arrested by the Federal Bureau of Investigation.
"You can not tolerate a government assassination on British soil - it is absolutely beyond the pale and needs a reaction", he said.