Downer spoke to FBI about Russian meddling in US election

The revelation the Australian government broke with diplomatic protocol and allowed Downer, then Australia's ambassador to the United Kingdom, to be interviewed by the Federal Bureau of Investigation could damage Australia's recently repaired relationship with US President Donald Trump.

The breakthrough stemmed from a night of heavy drinking Mr Downer had with former Trump campaign aide George Papadopoulos at the Kensington Wine Rooms in London in May 2016.

Downer reportedly notified US intelligence officials of his run in with Papadopoulos after the emails, which contained damaging information about Trump's former opponent Hillary ClintonHillary Diane Rodham ClintonOregon governor to face state rep in November Progressive pick Wild wins Dem primary for Pa. House seat Pelosi presses Ryan for classified briefing on election security MORE just as the aide said, began to leak to the public.

"Within hours of opening an investigation into the Trump campaign's ties to Russian Federation in the summer of 2016, the FBI dispatched a pair of agents to London on a mission so secretive that all but a handful of officials were kept in the dark", the New York Times reported on Wednesday.

"Crossfire Hurricane", a reference to a Rolling Stones lyrics, continued in secret as Trump publicly railed against the investigation, calling it a "witch hunt".

He has pleaded guilty to lying to officials, who he is now cooperating with.

He is co-operating with Mueller's investigation.

The bombshell revelation is buried deep inside a story about the early days of "Hurricane Crossfire", the FBI's counterintelligence investigation into possible collusion between the Trump campaign and Russian government.

Australian Prime Minister Malcolm Turnbull has carefully attempted to fix his relationship with Trump after the leaders had a fiery phone call about a refugee deal a week after the president moved into the White House.