Alexander Downer's infamous London bar meeting with former Donald Trump adviser George Papadopoulos is at the centre of a fiery US Senate committee hearing in Washington DC.
Republican and Democrat members of the Senate Judiciary Committee are grilling Justice Department Inspector General Michael Horowitz about his report into the FBI's handling of the 2016 probe into potential links between the Trump campaign and Russia.
Mr Trump and political allies claim the FBI was biased, and Mr Papadopoulos has alleged former Australian high commissioner to the UK Mr Downer and Australian intelligence were part of a deep state plot against him and the Trump campaign.
Mr Horowitz found no proof of that and said the FBI was right to start the probe.
The investigation began after Mr Downer told a US official Mr Papadopoulos had suggested at the May 2016 bar meeting that Russia may have dirt on Mr Trump's presidential rival Hillary Clinton.
"The inspector general confirmed there was an adequate predicate - meaning a legitimate factual and legal basis to investigate," the Democrat's ranking committee member Dianne Feinstein told the hearing on Wednesday.
"This report confirms the FBI opened the investigation after being told by Australia - a trusted foreign ally - that Trump adviser George Papadopoulos had learned in 2016, the month of April, Russia had and was willing to release information during the campaign that would be damaging to candidate (Hillary) Clinton.
"The IG report found this information provided the FBI with the factual basis that if true indicated activity constituting either a federal crime or threat to national security or both may have occurred."
The committee's Republican chairman Lindsey Graham ripped into the FBI's handling of the Russia investigation.
"What happened here is not a few irregularities," Senator Graham said.
"What happened here is the system failed.
"People at the highest level of our government took the law in their own hands."
Senator Feinstein blasted the "deep state" claims made by Mr Trump and allies.
"He has used this to dismiss the entire investigation as a witch hunt and hoax," she said.
"The IG report conclusively refutes these claims.
"This was not a politically motivated investigation.
"There is no deep state.
"Simply put, the FBI investigation was motivated by facts not bias."
Australian Associated Press
