Australian filmmaker James Ricketson has appeared briefly in a Cambodian court, six months after he was charged with being a spy.

Mr Ricketson was brought from jail to a court in Phnom Penh for questioning about his alleged espionage activities, but the case was postponed.

His lawyer, Sourng Sopheaktra, told the Phnom Penh Post authorities were still translating emails and documents found on his phone and laptop.

Photographs of James Ricketson flying a drone led to speculation over his arrest. ( Supplied )

Mr Sopheaktra said the court session was postponed until at least next week.

Mr Ricketson, 68, was arrested, detained and later charged with spying in June after he was photographed flying a drone over a political rally in Cambodia's capital.

He has been in prison for seven months — one month longer than the maximum limit for pre-trial detention. If convicted, he could face up to 10 years in jail.

Relatives and supporters have started an online petition urging the Australian Government to do more to secure his release from prison and to avoid "false persecution".

In a statement, the Department of Foreign Affairs and Trade said they were providing consular assistance to Mr Ricketson.

The filmmaker was widely known to be making a documentary about Cambodian politics and spent years following opposition leader Sam Rainsy.

James Ricketson (left) was making a documentary on former opposition leader Sam Rainsy. ( Supplied )

He has also been a vocal critic of Prime Minister Hun Sen, who has ruled Cambodia for 32 years.

In a 2014 blog post, Mr Ricketson compared Mr Sen to the Star Wars villain, Darth Vader.

He had also blogged about Australia's refugee resettlement policy and staged a one-man sit-in protest at Screen Australia that resulted in a restraining order.

In 2014 and 2016, he was convicted in Cambodian courts of defaming two separate child protection organisations.