Boris Johnson told Sky News that Britain wanted “all the suspects handed over for justice”.
He said Russia had already paid a “heavy price” over the poisoning, following the mass expulsion of diplomats, but added: “They should recognise that our sense of justice is not abated. Dawn Sturgess, an innocent member of the British public, died in that event and we want to see those suspects handed over.”
Mr Sergeev flew from Moscow to Heathrow airport on 2 March 2018, arriving around four hours before his colleagues, and stayed at a hotel in Paddington for two nights.
British counterterrorism police said Mr Sergeev had met with the two agents, who then travelled to Salisbury “on more than one occasion” over the weekend of the attack, but that no traces of novichok had been found at his hotel.
Mr Sergeev, who is aged around 50, flew back to Moscow from Heathrow at 1.45pm on 4 March, less than two hours after the nerve agent was applied to Sergei Skripal’s door.
The Crown Prosecution Service (CPS) has authorised the same charges against him as the two previous suspects, including the attempted murder of Mr Skripal and his daughter Yulia, the grievous bodily harm of police officer Nick Bailey, and the use of novichok as a chemical weapon.
The senior national coordinator for counterterrorism policing said Mr Sergeev had “operated as a team” with Alexander Mishkin, alias Alexander Petrov, and Anatoliy Chepiga, alias Ruslan Boshirov.
Metropolitan Police deputy assistant commissioner Dean Haydon told a press conference: “They came here separately in two groups – Petrov and Boshirov together, Fedotov by himself – [and] met, and without a doubt they’ve operated as a small team with a view to deploying novichok to kill people in this country.
“There is other intelligence that suggests they’ve been here before, but in other countries as well, working as a threesome and likely with others … in relation to similar attacks.”
British police are working with their counterparts in Bulgaria and the Czech Republic in relation to attacks linked to the same suspects. Investigators said there was no evidence that they had been involved in previous attacks in the UK.
In a statement in parliament on Tuesday, the home secretary called the attack an “appalling event which shook the whole country and united our allies in condemnation”.
Priti Patel did not announce any new sanctions or diplomatic expulsions against Russia, but told MPs that “discussions are taking place” with allies.
“We are looking at what other levers we have and what the next steps should be,” she said. “Should any of these individuals ever travel outside Russia, we will work with our international partners and take every possible step to detain them and extradite them to face justice.”
But senior Conservative MP David Davis, addressing the House of Commons, warned that Britain would remain at risk from similar attacks by Russian agents if the government did not take decisive action.
“If we do not act very firmly, they will do it again,” he said. “So we should act, not just against the GRU officers the home secretary has properly highlighted, but against all the manifestations of the Russian mafia state.
“If our government do not act more firmly now than we did after the Litvinenko murder, this will happen again.”
The charges announced on Tuesday do not cover the death of Ms Sturgess, a 44-year-old mother, who died in July 2018 after her boyfriend found a counterfeit perfume bottle containing the nerve agent.
Charlie Rowley gave Ms Sturgess what he believed to be a present, in Amesbury, near Salisbury, not knowing it contained enough novichok to kill “thousands of people”, police said.
He survived being poisoned after quickly washing the substance off, but Ms Sturgess died days after applying it to her skin in the belief it was perfume.
Mr Haydon said the investigation into how Mr Rowley found the bottle in June 2018, and where it had been during the period of time since the Skripal attack almost four months earlier, was still ongoing.
“There are still parts of the picture we have not been able to piece together,” he added. “We remain as determined as ever to bring those responsible for Dawn’s murder and Charlie’s poisoning to justice.”
The Russian government has denied any involvement in the 2018 attack. At a press conference on Tuesday, a spokesperson for the country’s ministry of foreign affairs, Maria Zakharova, accused the UK of “deliberately worsening relations” and of using the poisoning “to increase anti-Russian feeling in British society”.
“We condemn attempts to blame Russia,” she added. “We are trying to ascertain the truth and want exhaustive information from the UK, and [the UK] to fulfil obligations to give us consulate access to our citizens [Sergei and Yulia Skripal]”.
The CPS is not applying to Russia for an extradition warrant because the country’s constitution does not permit the extradition of its own nationals.
Instead, Interpol red notices have been issued, meaning the suspects can be arrested if they leave Russia – where all three men are believed to remain.
Mr Haydon said British authorities had seen “very little cooperation from Russia” since 2018, or in previous cases such as that of the murder of Alexander Litvinenko.
The European Court of Human Rights ruled on Tuesday that Russia was responsible for the 2006 killing of Mr Litvinenko, the ex-KGB officer who died an agonising death after he was poisoned in London with Polonium 210.
Mr Haydon added: “The Foreign Office will be talking on diplomatic channels to Russia, but from the police investigation side, our due process is to seek arrest warrants and circulate those through Interpol.
“If there is an opportunity to arrest those individuals and put them in front of a UK court to seek justice for those individuals mentioned or the people of Salisbury, we will do that.”
Mr Sergeev’s identity and other details of the attack were previously revealed by the investigative website Bellingcat, but Mr Haydon said it had taken time to gather evidence that reached the threshold for a criminal charge.
The investigation is still live, and police are investigating other suspects who may have been part of the poisoning operation targeting Mr Skripal, a former double agent who gave information to MI6.
“We have to follow due process and follow the evidence,” Mr Haydon added. “We are investigating a number of people. We can only evidentially prove [involvement by] the three we have announced, but we continue to investigate others as well, and if we reach the evidential standard to charge them we will.”
Police are appealing for anyone who saw Mr Sergeev in the UK, or may have information on the whereabouts of the counterfeit Nina Ricci perfume bottle between March and June 2018, to call the anti-terrorist hotline on 0800 789 321 or email firstname.lastname@example.org.