Australia's ambassador to the US Joe Hockey made an unsolicited offer to help with the controversial White House inquiry into Russian interference in the 2016 presidential election.
American and Australian officials have since met six times to discuss the probe, which was the subject of an unusual telephone call between Scott Morrison and Donald Trump.
Earlier this year, Mr Hockey suggested he make a proactive offer to take part in the so-called Barr inquiry.
Department of Foreign Affairs secretary Frances Adamson endorsed his proactive approach.
"I would say that Ambassador Hockey's forward-leaning approach on this ... was exactly what I as DFAT secretary would expect him to do," Ms Adamson told a senate estimates hearing on Thursday.
"An inquiry had been launched, Australia had been mentioned by the president, the foreign minister had indicated our willingness to assist."
"That's what he (Hockey) was doing, effectively saying we're here, we're ready to help in whatever way you want," she said.
Mr Hockey flagged his letter with the foreign minister before sending it in May and subsequently met with US attorney-general William Barr to discuss the inquiry.
Ms Adamson also shed more light on Mr Trump's call to Mr Morrison to ask for a point of contact.
Asked why the US president had called the prime minister directly, Ms Adamson explained it was simply because Mr Hockey was away at the time.
The secretary also confirmed she was the primary contact for the Barr inquiry, along with Mr Hockey and she met with Mr Barr in Washington in September.
Department officials refused to say whether Australia had handed over diplomatic cables to the Barr investigation, saying it would be prejudicial to the ongoing inquiry.
Mr Barr is spearheading the investigation into an earlier inquiry which looked at Russian interference in the 2016 US presidential election.
He is examining how the investigation by US Special Counsel Robert Mueller started.
Australia's former high commissioner to the UK, Alexander Downer, played a significant role in sparking the FBI investigation into the Trump campaign and Russia.
Mr Downer met with a Trump campaign adviser George Papadopoulos, who told him of damaging Russian information on election rival Hillary Clinton.
In his May letter, Mr Hockey said while Mr Downer was no longer employed by the government, Australia stood ready to provide the investigation with all relevant information.
Department officials refused to say whether Mr Downer was receiving legal or financial support from the government.
"Why is that a secret?" Labor senator Penny Wong asked. "This is public money."
Foreign Minister Marise Payne said the Barr inquiry was sensitive.
Senator Payne said she had full confidence Mr Downer acted appropriately.
Australian Associated Press