What is really going on in politics? Get our daily email briefing straight to your inbox Sign up Thank you for subscribing We have more newsletters Show me See our privacy notice Invalid Email

Britain's GCHQ spy agency played a key role in alerting US intelligence to contacts between Donald Trump's campaign team and Russian operatives, according to a report.

The electronic "listening" agency first became aware of suspicious "interactions" between figures connected to Trump and known or suspected Russian agents in late 2015, The Guardian reported, citing a "source close to UK intelligence".

The details were said to have been passed to the Americans as part of the routine exchange of information between the two intelligence communities.

Over the next six months - while Trump was campaigning to become president - a number of other Western agencies, including from France, Germany, Estonia, Poland, the Netherlands and Australia, were said to have passed on further information.

The information gathered by GCHQ - described by one source as the "principal whistleblower" - was said to have been picked up as part of the routine surveillance of Russian intelligence assets.

The Guardian said it understood that GCHQ at no point conducted any targeted operation against Mr Trump or members of his team and that the agency had not been proactively seeking information.

(Image: PA)

The claims are highly sensitive after Trump last month alleged that President Barack Obama had illegally "wiretapped" him in Trump Tower.

His press secretary Sean Spicer then cited a media report claiming the bugging had been carried out by GCHQ.

The allegation drew an extremely rare denial from GCHQ, which said the claim was "utterly ridiculous and should be ignored", while Britain's ambassador Sir Kim Darroch was given an assurance that it would not be repeated by the White House.

GCHQ merely declined to comment on the latest claims. A spokesman said: "It is long-standing policy that we do not comment on intelligence matters."

According to The Guardian, the FBI and the CIA were slow to pick up on the extent of the contacts between Trump's team and the Russians in the run-up to last year's presidential election - in part because US law bans them from monitoring the private communications of US citizens without a warrant.

"It looks like the (US) agencies were asleep," The Guardian quoted one source as saying.

"They (the European agencies) were saying: 'There are contacts going on between people close to Mr Trump and people we believe are Russian intelligence agents. You should be wary of this.'

"The message was: 'Watch out. There's something not right here."'

(Image: REUTERS)

GCHQ's then head, Robert Hannigan, was said to have passed material directly to CIA chief John Brennan in the summer of 2016.

After what was said to be a slow start, Mr Brennan used the intelligence to launch a major inter-agency investigation.

A number of inquiries are now under way in Washington into Trump campaign officials and Moscow, including an FBI-led counter-espionage investigation and inquiries by both the House and Senate intelligence committees.

Meanwhile former MI6 chief Sir Richard Dearlove has launched a fresh onslaught on the US administration over the previous claim that GCHQ spied on the Trump campaign on behalf of Mr Obama.

"This is simply deeply embarrassing - for Trump and the administration, that is," he said in an interview with Prospect magazine.

"The only possible explanation is that Trump started tweeting without understanding how the NSA-GCHQ relationship actually works."