Russian spies have launched a series of cyberattacks targeting British authorities and chemical weapons investigators following the Salisbury attack, it has been revealed.

The GRU military intelligence agency allegedly tried to strike the Porton Down defence laboratory and Foreign Office following the poisoning of Sergei Skripal in March.

In April, four Russians were arrested while attempting to launch a major “close access” cyberattack against the headquarters of the Organisation for the Prohibition of Chemical Weapons (OPCW) in the Hague.

Dutch investigators said the spies also intended to travel onwards to its accredited Spiez laboratory in Switzerland, which was testing novichok samples from Salisbury at the time.

Prime minister Theresa May and Dutch PM Mark Rutte condemned Russia’s actions in a joint statement, accusing Moscow of showing a “disregard for the global values and rules that keep us all safe”.

The Kremlin dismissed the fresh allegations as “fantasies” after denying any involvement in the Salisbury poisoning.

At briefings on Thursday, Whitehall officials confirmed British intelligence helped to thwart the operation against the OPCW.

The Russian men taken into custody travelled under the names Aleksei Sergeyvich Morenets, Evgenii Mikhaylovich Serebriakov, Oleg Mikhaylovich Sotnikov and Alexey Valeryevich Minin.

They had arrived in The Hague three days earlier on diplomatic passports and it is unclear whether they were using aliases.

Dutch security services expel Russian spies over cyber plot Show all 23 1 /23 Dutch security services expel Russian spies over cyber plot Dutch security services expel Russian spies over cyber plot Russian passports belonging to (top row) Oleg Sotnikov (left), Aleksei Morenets, (bottom row) Evgenii Serebriakov (left) and Alexey Minin, who have been named as the four GRU officers who tried to hack the global chemical weapons watchdog which is investigating the Salisbury nerve agent attack PA Dutch security services expel Russian spies over cyber plot On April 13 the officers parked a car carrying specialist hacking equipment outside the headquarters of the OPCW in The Hague Dutch Ministry of Defence/PA Dutch security services expel Russian spies over cyber plot Specialist equipment intended for the alleged hacking of WiFi networks of the Organisation for the Prohibition of Chemical Weapons (OPCW). Russia's military intelligence service has been accused of trying to hack the global chemical weapons watchdog which is investigating the Salisbury nerve agent attack PA Dutch security services expel Russian spies over cyber plot The Dutch counter-terrorism officers intervened to disrupt the operation and the four GRU officers were ordered to leave the country Dutch Ministry of Defence/PA Dutch security services expel Russian spies over cyber plot Mobile phones and a camera recovered from four GRU officers who were alleged to have hacked the WiFi networks of the Organisation for the Prohibition of Chemical Weapons (OPCW) PA Dutch security services expel Russian spies over cyber plot The four Russians arrived on diplomatic passports Netherlands Defence Ministry Dutch security services expel Russian spies over cyber plot Alexey Minin, who has been named as one of the four GRU officers who tried to hack the global chemical weapons watchdog which is investigating the Salisbury nerve agent attack PA Dutch security services expel Russian spies over cyber plot A car carrying hacking equipment used by GRU officers, travelling on official Russian passports, parked near the headquarters of the OPCW in The Hague Dutch Ministry of Defence/PA Dutch security services expel Russian spies over cyber plot Oleg Sotnikov, who has been named as one of the four GRU officers PA Dutch security services expel Russian spies over cyber plot Hacking equipment belonging to four Russian officers Dutch Ministry of Defence/AP Dutch security services expel Russian spies over cyber plot Evgenii Serebriakov, who has been named as one of the four GRU officers PA Dutch security services expel Russian spies over cyber plot Equipment found in possession of four Russian citizens Reuters Dutch security services expel Russian spies over cyber plot Photos of the Organisation for the Prohibition of Chemical Weapons (OPCW) and its surroundings taken on the 11 April, found on the phone of GRU officer Alexey Minin Dutch Ministry of Defence/PA Dutch security services expel Russian spies over cyber plot Equipment found in possession of four Russian citizens REUTERS Dutch security services expel Russian spies over cyber plot Aleksei Morenets, who has been named as one of the four GRU officers PA Dutch security services expel Russian spies over cyber plot Undated handout photo dated issued by the Dutch Ministry of Defence of a car carrying hacking equipment used by GRU officers, travelling on official Russian passports, parked near the headquarters of the OPCW in The Hague. PRESS ASSOCIATION Photo. Issue date: Thursday October 4, 2018. On April 13 the officers parked a car carrying specialist hacking equipment outside the headquarters of the OPCW in The Hague. At that point the Dutch counter-terrorism officers intervened to disrupt the operation and the four GRU officers were ordered to leave the country. See PA story POLITICS Russia. Photo credit should read: Dutch Ministry of Defence/PA Wire NOTE TO EDITORS: This handout photo may only be used in for editorial reporting purposes for the contemporaneous illustration of events, things or the people in the image or facts mentioned in the caption. Reuse of the picture may require further permission from the copyright holder. Dutch Ministry of Defence Dutch Ministry of Defence/PA Dutch security services expel Russian spies over cyber plot A combo of a taxi bill and a map, with a ride from a street next to the Main Directorate of the General Staff of the Armed Forces of the Russian Federation, GRU, to Sheremyetevo airport in Moscow, found in possession of one of four GRU officers AP Dutch security services expel Russian spies over cyber plot Yevgeny Serebryakov, an alleged Russian agent AFP/Getty Dutch security services expel Russian spies over cyber plot Dutch security services say they have foiled an attempted cyber attack targeting the international chemical weapons watchdog, during its investigations into the Salisbury attack. Netherlands Defence Ministry Netherlands Defence Ministry Dutch security services expel Russian spies over cyber plot Dutch security services say they have foiled an attempted cyber attack targeting the international chemical weapons watchdog, during its investigations into the Salisbury attack. Netherlands Defence Ministry Netherlands Defence Ministry Dutch security services expel Russian spies over cyber plot Dutch security services say they have foiled an attempted cyber attack targeting the international chemical weapons watchdog, during its investigations into the Salisbury attack. Netherlands Defence Ministry Netherlands Defence Ministry Dutch security services expel Russian spies over cyber plot Dutch security services say they have foiled an attempted cyber attack targeting the international chemical weapons watchdog, during its investigations into the Salisbury attack. Netherlands Defence Ministry Netherlands Defence Ministry Dutch security services expel Russian spies over cyber plot Dutch security services say they have foiled an attempted cyber attack targeting the international chemical weapons watchdog, during its investigations into the Salisbury attack. Netherlands Defence Ministry Netherlands Defence Ministry

Two of the passports – for the two “cyber operators” involved – were issued on the same day in April 2017 and have numbers just one digit apart.

The two GRU assassins who poisoned Mr Skripal in Salisbury were found to be travelling on fake passports that were three digits apart.

The men rented a Citroen C3, with a spacious boot, in Minin’s name to undertake their operation before going to their hotel.

Then on 13 April – the same day Donald Trump gave a press conference on US air strikes against Syria – they travelled in the car to OPCW headquarters, just off Johan de Wittlaan street in The Hague.

Pictures show that they parked outside the perimeter fence and opened the boot to use a computer, powered by a portable battery that had been bought in the Netherlands and connected to a wifi antenna which they hid from view under a coat.

As Dutch officers moved in, one of the men attempted to destroy some of the equipment but failed, leaving a computer and phones which revealed a sizeable amount of extra intelligence.

The men had cleaned out their hotel room, taking rubbish and any other items with them that might somehow allow counter-espionage agents to track them.

But once they were arrested they were escorted to the airport and put on a plane back to Russia, with UK officials explaining this would have been a decision by the Dutch government.

Russian passports belonging to four GRU officers who tried to hack the global chemical weapons watchdog (PA)

The British ambassador to the Netherlands, Peter Wilson, said the GRU officers stopped in the Hague had planned to travel onwards to an OPCW-approved laboratory in Speiz, Switzerland, which was testing Skripal samples.

At the same time, the OPCW was also analysing the substance used in a chemical attack on the Syrian rebel stronghold of Douma.

The watchdog later found chlorine was used in the Syrian incident, which US, British and French authorities attributed to Vladimir Putin’s ally Bashar al-Assad.

A spokesperson for the OPCW thanked security services involved in thwarting the attack and said it takes the security of its information systems and networks “very seriously”.

“Since early 2018, the organisation has observed increased cyber-related activities,” a spokesperson said. ”The OPCW technical secretariat has undertaken measures to mitigate them.”

Speaking of the attempted attack, Mr Wilson said: “This was not an isolated act.

“The unit involved, known in the Russian military as Unit 26165, has sent officers around the world to conduct brazen close-access cyber-operations.”

Equipment found on the Russian spies who allegedly tried to hack the OPCW (Ministerie van Defensie)

Officials also revealed that a GRU linked group called “Sandworm” had attempted to compromise Foreign Office and Porton Down computer systems immediately after the Salisbury poisoning in March.

They said that because the “spear phishing” attack, where hackers attempt to fool recipients into opening malicious emails by posing as someone else, did not work they are unsure what the Russians wanted to do.

Other attacks have been aimed at intercepting and monitoring communications, gaining information or disrupting systems and operations.

Among the men arrested in The Hague was one officer accused of conducting “malign activity” targeting Malaysian institutions investigating the downing of flight MH17 by rebels supplied with a Russian missile system in Ukraine.

Mr Wilson said another of the GRU officers arrested in the Hague had also previously visited Lausanne, Switzerland, in September 2016.

They connected to wifi in a hotel where a World Anti-Doping Agency conference was taking place, including Olympic committee officials who became victims of a cyberattack.

Putin calls Sergei Skripal a 'traitor' and a 'scumbag' in Moscow remarks

Malware from another GRU linked group, APT28, compromised an official’s laptop, the hotel’s system and then the IP addresses of the International Olympic Committee.

Then in May, Russian hackers sent emails impersonating Swiss federal authorities to OPCW employees in an effort to compromise their systems.

The US Justice Department charged seven Russian military intelligence officers with hacking anti-doping agencies and other organisations later on Thursday.

The indictment said the GRU targeted victims who had publicly supported a ban on Russian athletes in international sport competitions and condemned Russia’s state-sponsored athlete doping programme.

Prosecutors said the Russians also targeted a Pennsylvania-based nuclear energy company.

Following the same pattern seen internationally, the hacking was often conducted remotely and officers would only launch “close-access” operations in person if that tactic failed.

A British government official said the timing and targeting of cyberattacks suggested that when there are international investigations into Russian activity, the “GRU seems to deploy”.

Skripal attack aftermath – in pictures Show all 15 1 /15 Skripal attack aftermath – in pictures Skripal attack aftermath – in pictures Scene of attack Members of the emergency services in hazard suits fix the tent over the bench where Sergei and Yulia Skripal were found unconscious on a park bench in Salisbury in March 2018. Getty Skripal attack aftermath – in pictures Victim - Sergei Skripal The retired Russian colonel and former double agent for MI6 was in a critical condition in hospital for more than two months after being exposed to novichok in Salisbury. He was given refuge in the UK after being jailed in Moscow for treason. Mr Skripal came to Britain as part of a high-profile “spy swap” in 2010 in which four men were exchanged for ten Russian "sleeper agents" in the US. In this image he is speaking to his lawyer from behind bars in Moscow in 2006. AP Skripal attack aftermath – in pictures Victim - Yulia Skripal Yulia Skripal was struck down by a novichok poison alongside her father Sergei. Facebook Skripal attack aftermath – in pictures Scene of attack A police officer stands guard outside a branch of the Italian chain restaurant Zizzi where the pair dined at before falling ill. It was boarded off whilst investigators worked on the building and later found traces of the chemical weapon within it. AFP/Getty Skripal attack aftermath – in pictures Scene of attack Large areas of central Salisbury were cordoned off by police following the discovery of the Skripals. Traces of nerve agent were also found in The Mill pub. PA Skripal attack aftermath – in pictures Victim - Nick Bailey Detective Sergeant Nick Bailey, rushed to the aid of the Russian ex-spy and his daughter who were targeted with a nerve agent. He was hospitalized after aiding them and didn't leave until three weeks after the attack. Wiltshire Police/Rex Skripal attack aftermath – in pictures Police investigation - Skripal’s home Police believe they were poisoned at home, and detectives found the highest concentration of novichok on the front door of Mr Skripal’s house. Getty Skripal attack aftermath – in pictures Theresa May visits scene of attack Britain's Prime Minister Theresa May spokes with Wiltshire Police's Chief Constable Kier Pritchard near where the Skripal's were found. Britain expelled 23 Russian diplomats over the nerve agent poisoning and suspended high-level contacts, including for the World Cup on March 14. Theresa May told parliament that Russia had failed to respond to her demand for an explanation on how a Soviet-designed chemical, Novichok, was used in Salisbury. AFP/Getty Skripal attack aftermath – in pictures Skripal days before attack Sergei Skripal days before he was exposed to Novichok, that has left him fighting for life. ITV News Skripal attack aftermath – in pictures Police investigation - military involvement British soldiers were deployed soon after the attack to help a counter-terrorism investigation into the nerve agent attack. One of the places they were asked to help out with was Skripal's home and it's surrounding. They were asked to remove a vehicle connected to the agent attack in Salisbury, from a residential street in Gillingham. AFP/Getty Skripal attack aftermath – in pictures Police investigation Personnel in protective coveralls and breathing equipment cover an ambulance with a tarpaulin at the Salisbury District Hospital. AFP/Getty Skripal attack aftermath – in pictures Police investigation The investigation extended to the grave of Sergei Skripal's son Alexander in London Road cemetery. Getty Skripal attack aftermath – in pictures Police investigation The Counter Terrorism Policing Network requested assistance from the military to remove a number of vehicles and objects from Salisbury. EPA Skripal attack aftermath – in pictures Home Secretary visits scene of attack Home Secretary Amber Rudd visited the scene of the nerve agent attack at the Maltings shopping centre on 9 March. Getty Skripal attack aftermath – in pictures Yulia Skripal speaks for the first time Yulia Skripal, speaking for the first time, said she felt lucky to have survived the nerve agent attack in Salisbury which left her fighting for life. Ms Skripal said her life had been “turned upside down” by the assassination attempt. But the Russian national added she hoped to return to her homeland one day, despite the Kremlin being blamed for the attack. Reuters

Mr Wilson said: “The GRU has interfered in free elections and pursued a hostile campaign of cyberattacks against state and civilian targets.

“The GRU is an aggressive, well-funded official body of the Russian state. It can no longer be allowed to act aggressively across the world against vital international organisations, with apparent impunity.”

In a joint statement, Ms May and Mr Rutte said the GRU had shown “disregard for the global values and rules that keep us all safe”.

“The GRU’s reckless operations stretch from destructive cyber activity to the use of illegal nerve agents, as we saw in Salisbury,” they added.

“We will uphold the rules-based international system and defend institutions from those that seek to do them harm.”

Nato secretary general Jens Stoltenberg warned Russia to halt its “reckless pattern of behaviour”, adding: “Nato allies stand in solidarity with the decision by the Dutch and British governments to call out Russia on its blatant attempts to undermine international law and institutions.”

British officials say they do not know how Russia will react to the latest revelations, but are expecting a fresh swell of disinformation and conspiracy theories.