Sam Rainsy was on Wednesday refused entry to a flight from Malaysia to Indonesia, media reported late on Wednesday.
The "acting president" of the Cambodia National Rescue Party's announced return to the Kingdom on Independence Day on Saturday failed to occur.
Rainsy arrived in Kuala Lumpur airport on Saturday afternoon after boarding a flight from Paris, where he has been living for more than four years.
On Wednesday afternoon he was barred from boarding a flight at Kuala Lumpur airport to the Indonesian capital Jakarta, where he had planned to spend several days, AFP reported.
"Malaysia Airlines denied the boarding of [Rainsy] under the instruction of the Indonesian authorities," the airline said in a statement to AFP.
Reuters also reported that Malaysia Airlines said it had barred Rainsy from a flight from Kuala Lumpur to Jakarta on the instruction of Indonesian authorities.