An Australian filmmaker accused of spying in Cambodia has been denied bail by a Phnom Penh court.
A bench of four Supreme Court judges ruled on Tuesday that investigations into Ricketson's activities should continue in a lower court.
Ricketson, who has been held in pre-trial detention since June last year, arrived after the court delivered its decision and he was returned to prison immediately after his arrival.
He did not comment.
Ricketson, 68, was arrested in June and charged with "collecting information prejudicial to national security". He faces five to 10 years' jail if convicted.
Since his arrest, Ricketson has been detained in Cambodia's notorious Prey Sar prison where he has been kept under tight security.
His case has been linked to the opposition Cambodian National Rescue Party, which was dissolved by the courts amid a government crackdown on dissent that included the closure of media outlets.
His son Jesse Ricketson, who has moved to Cambodia to help his father with the case, said the family was "sorely disappointed" by the bail decision.
"We had all hoped very much that the court might return a positive result on the question of bail, allowing my father to sit through the investigation period in conditions more appropriate to his age," Mr Ricketson said 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.
"He has already lost 10 kilograms and is currently housed in a cell the size of 16m x 6m with 140 other men and we're just not sure how long he can endure these conditions."
The Ricketson family has appealed to the Cambodian government to help ensure the investigation be carried out with transparency and due process.
The statement describes Ricketson as a "kind, decent and honest man", who had over the last 22 years volunteered a much of his time and money to help poor families in Cambodia.
"We firmly believe James is innocent of espionage or any other crime and hope to see him return home soon."