Russian Foreign Ministry spokeswoman Maria Zakharova, during press conference, told journalists: “For over 2.5 years, UK has used the Salisbury incident to deliberately worsen relations… using it as an instrument of pressure… to increase anti-Russian feeling in British society”.

“We condemn attempts to blame Russia. We are ready for the truth. Our position. Has not changed.

“We are trying to ascertain the truth and want exhaustive information from the UK, and to fulfil obligations to give us consulate access to our citizens”.

Sergey Fedotov entered the UK on a flight from Moscow to London Heathrow, and had stayed in a hotel in central London between 2 and 4 March 2018 before returning to Russia, Priti Patel said.

The Home Secretary told MPs: “While in the UK he met with Petrov and Boshirov on more than one occasion in central London.

“The CT policing investigation has identified and established that Fedotov is in fact Denis Sergeev and he’s also a member of the GRU, and that all three individuals previously worked together for the GRU as part of additional operations outside of Russia.

“All three men are now wanted by UK police. Arrest warrants are in place for all three. The police have applied for an Interpol notice against Fedotov mirroring those already in place against the other two suspects.”

The Metropolitan Police has called on people who might have seen the suspects between 2-4 March 2018 to get in touch by calling 0800 789 321.

Theresa May, who was PM at the time of the Salisbury attack, called for the government to do “all it can” to bring the suspected attackers to justice.

She said in the Commons: “The use of a chemical weapon – Novichok – on the streets of Salisbury was an appalling crime which sadly led to the death of an innocent British woman, Dawn Sturgess.

“I congratulate the police and all those involved in identifying this third individual and in developing the evidence leading to charges against him.

“This is further confirmation that responsibility for this attack lies firmly in the hands of the Russian state.

“I urge the UK government to do all it can to bring the individuals concerned to justice.”

Priti Patel said that the government will be “relentless in pursuit of justice” for the victims of the “sickening and dispicable” novichok attacks.

The Home Secretary said that ministers are “committed” to introducing new legislation to counter state threats in the UK.

She added: “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.”

“We respect the people of Russia but we will do everything it takes to keep our country safe. We will work actively to deter and defend against the spectrum of threats emanating from Russia,” Ms Patel also said.

She said that the “appalling” incidents have “challenged the fundamental basis of international order”.

The Metropolitan Police has said that detectives uncovered evidence confirming the real identities of the three suspects.

‘Sergey Fedotov’ is actually Denis Sergeev, ‘Alexander Petrov’ is Alexander Mishkin, and ‘Ruslan Boshirov’ is Anatoliy Chepiga.

“They have all previously worked together for the ‘GRU’ in operations outside Russia,” the Met said.

The force has called on people who might have seen the suspects in the UK, between 2-4 March 2018, to get in touch by calling 0800 789 321.

British police say Denis Sergeev is an agent in Russian’s GRU military intelligence service, aged around 50.

Further details of his life and career have previously been revealed by the investigative website Bellingcat, but not confirmed by authorities.

The Independent’s security correspondent Lizzie Dearden has all the details about Sergeev.

Nick Price, CPS Head of Special Crime and Counter Terrorism Division, said: “We are working closely with the police to ensure that, where possible, those responsible for this attack are brought to justice.

“Our specialist prosecutors have considered the additional evidence against the third suspect and have concluded that there is sufficient evidence to provide a realistic prospect of conviction and that it is clearly in the public interest to charge Sergey Fedotov, who is a Russian national, with a number of offences including conspiracy to murder, attempted murder and the use and possession of a chemical weapon.

“We will not be applying to Russia for the extradition of Sergey Fedotov as the Russian constitution does not permit extradition of its own nationals. Russia has made this clear following requests for extradition in other cases. Should this position change then an extradition request would be made.

“A realistic prospect of conviction means that the CPS is satisfied on an objective assessment that the evidence can be used in court and that an objective, impartial and reasonable jury hearing the case, properly directed and acting in accordance with the law, is more likely than not to convict Sergey Fedotov of the charges. It is of course for a jury to decide whether the evidence is enough for them to be sure of the suspect’s guilt.”

Downing Street acknowledged it would be “futile” to seek to bring Denis Sergeev to justice while he remained in Russia.

A No 10 spokesman said: “We don’t have an extradition treaty with Russia and, as we have found with other cases such as that of Litvinenko, any formal extradition request is futile.”

The UK will raise with the Russian ambassador on Tuesday the issue of a third Russian who has been charged in absentia with the 2018 Novichok murder attempt on a former double agent, Prime Minister Boris Johnson’s spokesman said.

“The FCDO (Foreign, Commonwealth and Development Office) will be raising this matter with the Russian ambassador today,” the spokesman said.

“If these individuals should ever travel outside Russia we will do everything we can to detain them, to extradite them and to bring them to justice here in the UK.”

Wiltshire Police and Crime Commissioner Philip Wilkinson said: “My thoughts, and those of my office, remain with Dawn Sturgess’ family and friends, alongside the other victims who have had their lives devastated by this incident.

“While today’s announcement is important, it is vital we remember a member of our community was killed and others left changed and traumatised by the barbaric use of a nerve agent on UK soil.

“Our community has rebuilt, and those other victims are coming to terms with the long-lasting implications, so my hope now is the perpetrators will have their appalling crimes levelled against them and all of the victims will see justice served in their names.

“I am democratically elected to hold our police force to account, it would be widely welcomed if some foreign security services demonstrated that same accountability.”