British intelligence reportedly provided a vital tipoff to the US in 2015 about the extent of Russian hacking on the presidential election.

The report on the UK’s involvement came after US intelligence agencies published an unclassified version of their finding that Vladimir Putin ordered a multi-pronged operation to interfere in the election in favour of Donald Trump.

The New York Times, citing “two people familiar with the conclusions” of the report, said British intelligence was “among the first” to raise the alarm in autumn 2015 that Moscow had hacked the computer servers of the Democratic National Committee.

The UK’s role suggests that the compromise of email exchanges among senior Democrats was spotted when voice intercepts, computer traffic or agents picked up content of the emails flowing towards Moscow.

Over the course the campaign, British officials were as alarmed as their US counterparts over the extent of contacts between Trump advisers and Moscow and by Trump’s consistently pro-Russian stance on a range of foreign policy issues.

However, those officials now say they are in a difficult position since the election, as Theresa May’s government is striving to solidify ties with the incoming Trump administration, in part to counter-balance the UK’s accelerating drift from Europe.

To that end, Downing Street took the unusual step last week of briefing against US secretary of state John Kerry for his denunciation of Israeli settlements on the West Bank, although his remarks closely reflected longstanding UK policy.

Allegations about the depth and nature of contacts between the Trump camp and Moscow have been passed to the FBI but it is unclear whether they are the subject of a full investigation.

There was no reference to them in the public version of the joint intelligence report on Russian interference in the election, compiled by the CIA, FBI and NSA.

“It is not surprising that the report did not reference any involvement of US persons or ongoing criminal investigations,” said Susan Hennessey, a former counsel on cybersecurity at the NSA.

“The government has very specific processes for making those kinds of allegation and typically only does so in criminal indictments in order to preserve the rights of citizens, who retain the presumption of innocence.

“That said, the question of whether there was any criminal conduct in the United States remains a relevant open question.”

A classified version has been prepared for Congress, and a top secret version has been shown to Barack Obama, Trump and a few other officials with high-level clearance.

The unclassified version makes the unprecedented claim that the Russian leadership conducted a concerted and well-resourced attempt to skew an US election in favour of one candidate.

“We assess Russian president Vladimir Putin ordered an influence campaign in 2016 aimed at the US presidential election,” the joint finding by the CIA, FBI and NSA said.

“Russia’s goals were to undermine public faith in the US democratic process, denigrate Secretary Clinton, and harm her electability and potential presidency. We further assess Putin and the Russian government developed a clear preference for President-elect Trump. We have high confidence in these judgments.”

The report said Putin developed a preference for Trump because of “many positive experiences working with Western political leaders whose business interests made them more disposed to deal with Russia, such as former Italian prime minister Silvio Berlusconi and former German chancellor Gerhard Schroeder”.

Another motive, according to the report, was that a Trump victory was seen “as a way to achieve an international counterterrorism coalition against the Islamic State in Iraq and the Levant (ISIL)”.

In a new series of tweets on Saturday, the president-elect said: “Having a good relationship with Russia is a good thing, not a bad thing. Only ‘stupid’ people, or fools, would think that it is bad! We have enough problems around the world without yet another one.”

He added: “When I am President, Russia will respect us far more than they do now and both countries will, perhaps, work together to solve some of the many great and pressing problems and issues of the WORLD!”

Trump has frequently derided the US intelligence community, highlighting its failings over Iraq’s non-existent weapons of mass destruction in the runup to the 2003 invasion.

After meeting the intelligence chiefs on Friday in New York, he issued a statement affirming his respect for the work of the agencies, and pledged to take the threat of cyberwarfare seriously.

However, he lumped in Russia with China and “other countries” in describing the threat and claimed that the intelligence report found no evidence that foreign interference had influenced the outcome of the election.

In fact, the report did not address the question of the impact on the result.

Although it made strong claims about Russian interference, the public version of the report offered little fresh evidence. Seven of its 13 pages were taken up by a four-year-old assessment of the state-owned channel Russia Today (RT) as an arm of Kremlin propaganda.

“These seven pages written by the US intelligence community comprise what is perhaps the greatest and most generous Christmas gift in the history of Russian Orthodoxy, which celebrates the birth of Christ on Saturday 7 January,” wrote Kevin Rothrock, web editor of the Moscow Times.

“Thanks to the CIA, FBI and NSA, Russia Today can count on continued, likely expanded, Kremlin funding.”

“The inclusion of the 2012 annex was strange and may have actually undercut the strength of the overall document,” said Hennessey, the former NSA lawyer who is now a fellow in national security in governance studies at the Brookings Institution.

“My best guess is that once the classified version of the report was stripped of sensitive information for public release, the resulting document was extremely thin and there was a desire to add in something to make it appear more substantial.”

The focus on RT is likely to deepen the mutual suspicion between Trump’s designated national security adviser, Michael Flynn, a former head of the Defense Intelligence Agency, and the current intelligence community.

In 2015, Flynn flew to Moscow at RT’s expense to attend a dinner marking RT’s 10th anniversary. He was seated at the same table as Putin and has been a regular guest on RT shows.