Former spy Christopher Steele shared explosive dossier on Donald Trump and Russia with British authorities because of 'serious risks to national security'

A former British spy said he was “duty bound” to share an explosive dossier on Donald Trump’s links to Russia with British authorities because his administration “might pose a serious risk to UK national security.”

Christopher Steele, a 22-year veteran of MI6, revealed in court that he approached a Government national security official just days after Donald Trump was elected because he was so concerned about what he had unearthed in a fact-finding mission on behalf of Hillary Clinton's presidential campaign.

The 56-year-old was speaking out for the first time about his leaked dossier because he is being sued over claims it makes about computer hacking by a Russian businessman, Aleksej Gubarev.

In a written statement, Mr Steele said: "The intelligence recorded in the pre-election memoranda had important potential national security implications for the UK, as well as the US.

"The intelligence in the pre-election memoranda suggested that Donald Trump and his administration might pose a serious risk to UK national security in relation to the receipt of sensitive intelligence from British sources and operations, especially sources/operations in or in relation to Russia."

He added: "Since the intelligence I had gathered had important implications for UK national security following Donald Trump's election as President, I considered myself duty bound to provide it to the appropriate national security authorities in the UK."

The Telegraph revealed last year that the official was Sir Charles Farr, the chair of the Joint Intelligence Committee - the body in charge of assessing intelligence.

He had also been one of Theresa May’s top counter-terrorism advisers at the Home Office.

It is also understood that Alex Younger, the MI6 chief, and Andrew Parker, the MI5 director general, were informed of the dossier.

In a dramatic testimony at the High Court in London, Mr Steele said that he was “shocked and horrified” that Buzzfeed had published his secret memorandum in full and unredacted in “one of the most irresponsible journalistic acts ever.”

The dossier contained allegations of misconduct, conspiracy, and co-operation between Donald Trump's presidential campaign and the government of Russia during the 2016 election. They were never proven.

Mr Steele was giving evidence after being sued for libel by Aleksej Gubarev, a Russian venture capitalist who runs the IT business Webzilla and was named in the dossier.

Mr Gubarev claims he was defamed by the material, which made allegations that they had "knowing involvement" in the hacking of the computer systems of the Democratic National Committee before the election.

Mr Steele and the corporate intelligence company he co-founded, Orbis Business Intelligence, are fighting the claim and insist the publication of the dossier by Buzzfeed in January 2017 was “unauthorised”.

Yesterday, in a written witness statement, Mr Steele said the publication was “one of the most irresponsible journalistic acts ever.”

“In my view, Buzzfeed did the kremlin's work for them,” he said.

Describing his reaction as “shock and horror” he said he was angered at what had happened, and added: “I wonder if Buzzfeed have reflected on the lives and livelihoods they put at risk by publishing the dossier, or the shutter it has drawn down on any further collection efforts on this issue and others by anybody or any government agency.”

If he had known the material was to be released, Mr Steele said: “I would certainly have done whatever I could to prevent this."

Mr Steele also said the publication of his confidential dossier was “professionally ruinous” for his company.

"Our business depends on the confidentiality of our clients and sources. If these are exposed to the world, no one will contract or hire Orbis to do discreet work on their behalf.

“It therefore would be professionally ruinous - and also morally repugnant - for us to do anything that could risk exposing a source, especially in a ruthless, lawless place like Russia, as a result of any such (especially media) exposure."

The High Court case is set against a remarkable backdrop of the publication of a long-awaited report by Parliament’s intelligence watchdog on Russia’s influence in Britain.

Russia's influence in British politics and society is the "new normal", and the UK Government has "badly underestimated" the response needed, the report said.

The hearing continues.

Listen to Crossfire, a six-part Telegraph podcast revealing the untold story of Britain's role in the Trump-Russia scandal, revealed by those who saw it firsthand, on The Telegraph website, Apple Podcasts, Spotify or your preferred podcast app.