"At this stage, we have not received any information to suggest that anything other than due process is being afforded to him," DFAT executive Andrew Todd told a Senate estimates hearing on Thursday.
Source: Pacific Press/Sipa USA
Last year, Mr Assange withdrew consent for information about him to be given to the Australian government.
The Wikileaks founder reported being handcuffed 11 times, stripped naked twice and having his case files confiscated after the first day of his trial.
"We sought advice from the prison in relation to those reports," Mr Todd said.
"We were advised that other than the issue with legal documents, they were standard prison-to-court and court-to-prison procedures."
Senator Payne said there had been "an acknowledgement an error was made" in relation to the legal documents and they were returned.
"I trust we have determined that won't occur again," she told the committee.
It was revealed last week that meetings between Mr Assange and his lawyers inside the Ecuadorian embassy in the United Kingdom were allegedly secretly filmed.
Those claims are subject to separate legal proceedings in Spain, which Australian officials are also monitoring.
The UN special rapporteur on torture has raised concerns about the continued deterioration of Julian Assange's health since his arrest and detention earlier this year, warning his life was at risk.
Mr Assange is currently is being held at the high-security Belmarsh Prison.
Independent MP Andrew Wilkie, who recently visited Mr Assange inside the facility, told SBS News the Wikileaks founder is effectively being held in "solitary confinement" and his attendance in court sees him "quarantined from his lawyers."
"He is being treated very poorly and in my opinion not consistent with what we would regard as reasonable standards for someone who is not actually charged with anything," he said.
"He's basically just been detained facing an extradition trial - I think it is completely unreasonable."
Senator Payne said she raised Australia's expectations about Mr Assange's treatment with British Foreign Secretary Dominic Raab during his visit to Canberra three weeks ago.
Mr Assange is facing extradition to the United States on 17 espionage charges, including conspiring to receive, obtaining and disclosing national security information.
All bar one offence carries a maximum penalty of 10 years in prison, but Australian officials have been advised people charged with similar offences in the United States have not received cumulative sentences.
None of the offences Mr Assange faces carries the death penalty, but department officials confirmed he could face further charges in the United States if he is extradited.