In a speech in Washington, Jeremy Fleming (pictured) called on the international community to reject the Kremlin's 'brazen determination to undermine the international rules-based order'

The head of GCHQ has said the agency will use the 'full range of tools' against the Kremlin after two Russian intelligence officers were accused of carrying out the Salisbury nerve agent attack.

In a speech in Washington, Jeremy Fleming called on the international community to reject Moscow's 'brazen determination to undermine the international rules-based order'.

On Wednesday, two Russian nationals, said to be members of Russia's military intelligence service the GRU, were identified as suspects by police investigating the poisoning of former spy Sergei Skripal in March.

Mr Fleming said the intelligence community had supported police in a 'painstaking' and 'highly complex' investigation into what happened.

He said: 'We have ascertained exactly who was responsible and the methods they used.

'As you would expect, teams from across GCHQ have worked tirelessly with partners at home and abroad to ensure that our world-class intelligence has informed that investigation.

'Yesterday two GRU operatives were named and arrest warrants issued. The threat from Russia is real. It's active.

'And it will be countered by a strong international partnership of allies. Able to deploy the full range of tools from across our national security apparatus. And ready to reject the Kremlin's brazen determination to undermine the international rules-based order.'

It is the latest rebuke aimed at Moscow by a British spy chief since the Salisbury attack.

In May, Andrew Parker, the Director General of MI5, described the Russian Government as 'chief protagonist' among 'hostile actors'.

Alexander Petrov (left image) and Ruslan Boshirov (right image) are wanted by British authorities after the chemical attack in March this year

In other remarks, Mr Fleming, the Director of GCHQ, said encryption 'enables us all to live safer online lives'.

But he warned: 'Its ubiquity brings anonymity to terrorists, paedophiles and cybercrime gangs who law enforcement and intelligence agencies are trying to stop. And it's getting worse.'

It goes without saying that there has to be close co-operation with technology companies, he said.

'We are confident solutions exist,' Mr Fleming continued. 'And where they do, proportionality, as in everything else we do, is key.

'They should be limited in scope and scalability, supported by modern legislation and with strong oversight to maintain public confidence.'

He also said the signals intelligence partnership between the UK and America was 'one of the jewels in the crown of the 'Special Relationship'.

Moscow has repeatedly denied involvement in the poisoning.

Mr Fleming said GCHQ (pictured) would use the 'full range of tools' against Russia's spy agency after two intelligence officers were accused of carrying out the Salisbury attack

Yesterday Russia claimed the UK had been 'mendacious' and was trying to unleash 'disgusting anti-Russian hysteria' during talks at the United Nations.

Diplomat Vasily Nebenzya told the UN security council: 'I'm not going to go through the list of this whole unfounded and mendacious cocktail of facts.

'London needs this story for just one purpose - to unleash a disgusting anti-Russian hysteria and to involve other countries in this hysteria.'

Mr Skripal and his daughter Yulia were left critically ill after being exposed to the military grade nerve agent Novichok in Salisbury in March.

Detectives believe it is likely the two suspects, thought to be aged around 40, travelled under aliases and that Petrov and Boshirov are not their real names.

Officers have formally linked the attack on the Skripals to events in nearby Amesbury when Dawn Sturgess, 44, and her partner Charlie Rowley, 45, were exposed to the same nerve agent.

Ms Sturgess died in hospital in July, just over a week after the pair fell ill.