James Ricketson leaving Cambodia

Australian filmmaker James Ricketson is expected to arrive in Sydney on Sunday night after he was given a royal pardon in Cambodia.

Ricketson, 69, was sentenced to jail for six years on August 31 for espionage in a trial that was widely criticised by human rights activists and politicians in Australia.

He was flying a drone with a camera on it over an opposition Cambodia National Rescue Party (CNRP) rally and charged with collecting information that may undermine national defence.

Cambodian King Norodom Sihamoni issued the royal pardon on Friday evening, and Ricketson was due to leave the country on Saturday, a Cambodian immigration spokesman told AAP.

Ricketson's lawyer, Kong Sam Onn, said his client had been released from jail on Friday evening and went to his son Jesse's house in Phnom Penh.