Just what Papadopoulos told the three congressmen who turned up on Thursday for the closed-door meetings before the Republican-controlled House judiciary and oversight and government reform committees was not immediately clear.

The two Republicans and one Democrat congressmen were tight-lipped with specifics about the Chicago-born 31-year-old’s testimony.

Papadopoulos, who has regularly launched Twitter tirades at former Australian high commissioner to the UK Downer in recent weeks, was careful with his words after he emerged from the meeting on Capitol Hill.

“I’m glad both sides were able to ask me any questions that they had,” Papadopoulos told reporters before his lawyer drew him away.

Attendance was sparse because Congress is in recess and most members are campaigning in their districts before next month’s crucial midterm elections.

Mark Meadows, one of two Republicans, described Papadopoulos as a “critical witness” into finding out why the FBI launched its mid-2016 probe into potential collusion between Russia and Trump’s presidential campaign.

“What we’re finding, without talking about specifics of what’s going on, is that the whole reason that this investigation was opened up was certainly not one built on a solid foundation,” Meadows said.

Jamie Raskin, the lone Democrat congressman, described Papadopoulos’ testimony as continuing “the kangaroo court of the Republican efforts to undermine” Special Counsel Bob Mueller’s Russian investigation.

Raskin questioned Papadopoulos’ credibility after he was prosecuted by Mueller and sentenced last month to 14 days jail for lying to the FBI.

“I see this whole thing as a footnote to a sideshow of a wild goose chase,” Raskin said.

“There is a right-wing echo chamber that traffics in rumours and lies and fake news.”

The congressional committees are investigating the FBI and Justice Department’s handling of the probe into Trump’s campaign and links to Russia.

A May, 2016, London drinks session between Downer and Papadopoulos has been credited with starting the FBI probe.

Downer said Papadopoulos told him “the Russians might use material” they had on Trump’s presidential rival Hillary Clinton in the lead-up to the election, “which may be damaging”.

Downer forwarded the information to Canberra and it made its way to the FBI.

Papadopoulos has said he has no recollection of offering the tip to Downer but he has repeatedly accused Downer and the Australian and UK governments of spying on him and attempting to sabotage Trump’s election campaign.

Downer has denied Papadopoulos’ spying claims.

Meadows said Papadopoulos’ testimony did point to new links between foreign governments and the Obama administration.

“Two new names came up today and in those conversations, their connection to either the US government or foreign governments is of key concern to a number of us that are asking questions,” Meadows said.

– AAP