The UK government was given details last December of allegedly extensive contacts between the Trump campaign and Moscow, according to court papers.

Reports by Christopher Steele, a former MI6 officer, on possible collusion between the the Trump camp and the Kremlin are at the centre of a political storm in the US over Moscow’s role in getting Donald Trump elected.

It was not previously known that the UK intelligence services had also received the dossier but Steele confirmed in a court filing earlier this month that he handed a memorandum compiled in December to a “senior UK government national security official acting in his official capacity, on a confidential basis in hard copy form”.

The court papers say Steele decided to pass on the information he had collected because it was “of considerable importance in relation to alleged Russian interference in the US presidential election”, that it “had implications for the national security of the US and the UK” and “needed to [be] analysed and further investigated/verified”.

The December memo alleged that four Trump representatives travelled to Prague in August or September in 2016 for “secret discussions with Kremlin representatives and associated operators/hackers”, about how to pay hackers secretly for penetrating Democratic party computer systems and “contingency plans for covering up operations”.

Between March and September, the December memo alleges, the hackers used botnets and porn traffic to transmit viruses, plant bugs and steal data online from Democratic party leadership. Two of the hackers had been “recruited under duress by the FSB” the memo said. The hackers were paid by the Trump organisation, but were under the control of Vladimir Putin’s presidential administration.

Trump has rejected the allegations of collusion as a smear campaign. His lawyer, Michael Cohen, one of Trump representatives named in the memo, has described the claims in the memo as “totally fake, totally inaccurate”, and has said he had never been to Prague.

Since the memo became public in January, Steele had not spoken about his role in compiling it but he and his company, Orbis Business Intelligence Limited, have filed a defence in the high court of justice in London, in a defamation case brought by Aleksej Gubarev, a Russian venture capitalist and owner of a global computer technology company, XBT, and a Dallas-based subsidiary Webzilla.

Gubarev, who was named along with his company in the December memo as being involved in hacking operation, has denied any such involvement and is also suing Buzzfeed in the US courts for publishing the December memo alongside Steele’s earlier reports on election hacking.

A statement by Steele’s defence lawyers, endorsed by the former MI6 agent, said Orbis was hired between June and November last year by Fusion GPS, a Washington-based research consultancy to look into Trump’s links with Russia.

In that period, Steele produced 16 memoranda citing mostly Russian sources as describing a web of alleged contacts and collusion between Trump aides and Russian intelligence or other Kremlin representatives.

The document said that he passed the memos to Fusion on the understanding that Fusion would not disclose the material to any third parties without the approval of Steele and Orbis. They did agree to Fusion providing a copy to Senator John McCain after the veteran Republican had been told about the existence of Steele’s research by Sir Andrew Wood, a former UK ambassador to Moscow and an Orbis associate, at a conference in Canada on 8 November.

Senator McCain handed a copy of the Steele memos to James Comey, the FBI director, on 9 December.

After delivering these reports, the court papers say Steele and Orbis continued to receive “unsolicited intelligence” on Trump-Russia links, and Steele decided that to draw up another memo with this new information which was dated 13 December.

He handed one copy over to the senior British national security official and sent an encrypted version to Fusion with instructions to deliver a hard copy to Senator McCain.

The defence argues that Steele and Orbis were under a duty to pass on the information “so that it was known to the United Kingdom and United States governments at a high level by persons with responsibility for national security”.

Steele and Orbis say they never gave any copies to news organisations although Steele said he gave off-the-record briefings about the dossier to a small number of journalists in late summer and early autumn 2016. The defence brief argues that neither Steele nor Orbis is liable for Buzzfeed’s decision to print the document.

The Steele dossier was referred to in an intelligence briefing provided by the FBI and US intelligence agencies to Obama and Trump in January. Comey has confirmed that counter-intelligence investigations are under way into possible links between Trump associates and Moscow, and CNN has reported that the FBI used the dossier to bolster its investigations.