Attorney-General Mark Dreyfus was not contacted about a new FBI probe into WikiLeaks co-founder Julian Assange.

US authorities are reportedly trying to gather evidence against Mr Assange, and have requested to interview novelist Andrew O’Hagan about his previous work as a ghostwriter on the Australian’s autobiography.

Asked if he was aware of an investigation, Mr Dreyfus said he was not until he read reports about it on Thursday morning.

“Our position has been very clear for a long time now that this matter has gone on for too long, and that remains our position,” he told ABC Radio.

“We’re doing everything we can to make sure that it’s brought to an end.”

Last month, Stella Assange addressed the National Press Club, where she pleaded for an end to her husband’s detention, as he awaits extradition to the US to face espionage charges.

The Bring Julian Assange Home Parliamentary Group met with ambassador Caroline Kennedy at the US Embassy in Canberra last month to advocate for his release.

– AAP