British spies are ready to counter an "active and real threat" posed by the "brazen Kremlin", the head of GCHQ has warned.

Jeremy Fleming said the government's cyber intelligence agency could "deploy the full range of tools from across our national security apparatus" to target Russia's GRU intelligence agency and its agents.

During a speech at the Billington Cybersecurity Conference in Washington, Mr Fleming said Britain is "ready to reject the Kremlin's brazen determination to undermine the international rules-based order".

The warning comes after the UK and Russia clashed at a UN Security Council meeting over the Salisbury nerve agent attack, believed to have been carried out by two GRU agents.

Image: Jeremy Fleming said the Salisbury investigation had been 'painstaking'

Whitehall sources say Britain has the "offensive cyber capability" to target the GRU and individuals linked to it, The Telegraph reports.


In other remarks, Mr Fleming said the UK's intelligence agencies had supported police in a "painstaking" investigation into the Salisbury attack.

He added: "We have ascertained exactly who was responsible and the methods they used.

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

On Wednesday, two Russian nationals were identified as suspects by police investigating the poisoning of former spy Sergei Skripal and his daughter Yulia in March.

The father and daughter were left critically ill after being exposed to the nerve agent novichok and were found unconscious on a bench in the Wiltshire city.

During last night's UN meeting, Russia claimed the UK was trying to unleash "disgusting anti-Russian hysteria" by naming suspects Alexander Petrov and Ruslan Boshirov.

The full story behind the novichok poisonings

Russian ambassador Vasily Nebenzya said: "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."

In response, Dame Karen Pierce, the UK's representative at the UN, said Russia had "played dice with the lives of the people of Salisbury."

Image: Dame Karen Pierce said Russia had 'played dice with the lives of the people of Salisbury'

"We have clear evidence of Russian state involvement in what happened in Salisbury," she told the meeting.

US President Donald Trump, German Chancellor Angela Merkel, French President Emmanuel Macron and Canadian Prime Minister Justin Trudeau have issued a joint statement, agreeing with the British assessment that the attack was "almost certainly approved at a senior government level" in Moscow.