Australian filmmaker James Ricketson, who is awaiting trial on contentious “espionage” charges, had his bid for bail rejected in absentia by Cambodia’s Supreme Court today.

The bail decision was handed down before Ricketson arrived at the court, and the prison van transporting him immediately turned around upon entering the court compound and departed.

His lawyer, Peung Yok Hiep, said the bail request was rejected at Cambodia’s highest court because the investigation into Ricketson – which includes combing his emails and camera equipment – was not yet finished at the lower court.

Ricketson, 68, was arrested in June last year after he was spotted flying a drone above an opposition party rally, and was accused of gathering information that could undermine Cambodia’s national security with the intent to pass it on to a foreign entity. If found guilty, he could face up to 10 years in prison.

He has spent the past seven months at Cambodia’s notoriously overcrowded Prey Sar prison. Ricketson was recently moved to a 16-by-6-metre cell containing 140 inmates, according to family members, who are concerned for his health and well-being.

“Our family is sorely disappointed by today’s verdict,” said Jesse Ricketson, James’s son, in a statement. “As he’s almost 70, our family is very concerned about my father’s health in the lead up to the hot period in March and April.”

Jesse’s partner, Alexandra Kennet, was present at court and said the family was especially disappointed the bail rejection was handed down in James’s absence.

“But we do hope that we can see the case move forward transparently and as swiftly as possible,” she added.

Ricketson and his lawyers have argued the spying charges are politically driven, due to his perceived links to leading opposition party figures. He has also come into conflict with child protection NGOs, who allege he defamed them.

The opposition Cambodia National Rescue Party was dissolved by the Supreme Court in November over accusations it was fomenting a foreign-backed “revolution”, which authorities have done little to substantiate. Its leader, Kem Sokha, was arrested for “treason” in September.

Support in Ricketson’s native Australia has grown after former Al Jazeera journalist Peter Greste, who was jailed in Egypt on widely panned allegations of damaging national security, called attention to his plight. A petition demanding his release garnered more than 66,000 signatures.

“James is an excellent and loving father, uncle and brother. He is a kind, decent and honest man, and has, over the last 22 years, volunteered a lot of his time and money to help poor families in Cambodia,” Jesse said.

“We firmly believe James is innocent of espionage or any other crime and hope to see him return home soon.”

Updated: Wednesday 31 January 2018, 6:52am