Australian filmmaker James Ricketson is expected to return to Sydney today after being pardoned on an espionage conviction, but his lawyer says "he will be back in Cambodia".

Key points: Ricketson was sentenced last month to six years imprisonment on espionage charges

Ricketson was sentenced last month to six years imprisonment on espionage charges He was arrested after using a drone to photograph a political rally

He was arrested after using a drone to photograph a political rally The royal pardon doesn't stop Ricketson from re-entering Cambodia

The 69-year-old Australian, who had been making documentaries in Cambodia for more than 20 years, was convicted three weeks ago and sentenced to six years in prison.

However, he received a royal pardon on Friday night and was expected to arrive in Sydney at 8:00pm tonight.

It was alleged that he had been using his documentary projects and humanitarian work to collect information that would jeopardise national security.

He was arrested after flying a drone to photograph a rally of the now dissolved Cambodian National Rescue Party.

Australian filmmaker James Ricketson was arrested after flying a drone at a political rally. ( Reuters: Samrang Pring )

Ricketson repeatedly insisted he had no political agenda and his work making documentary films was journalistic in nature.

His August 31 conviction was met with only lukewarm public concern from Australia's prime minister and foreign minister.

Their public stance was criticised, but it also led to speculation that an understanding might have been reached with Cambodian authorities for Ricketson's early release.

Ricketson's lawyer, Kong Sam Onn, said on Friday (local time) that his client would go first to Phnom Penh and then travel to Australia.

"James will go back to his home country after he is released, but later he will be back to Cambodia because the pardon letter doesn't bar him from re-entering Cambodia," he said.

However, there is no official statement guaranteeing he will be readmitted.

Sorry, this video has expired James Ricketson's family told 7.30 they were deeply concerned about the state of the filmmaker's health.

AP/ABC