Sam Rainsy was stopped at Paris' Charles de Gaulle airport on Thursday evening from boarding his flight to the Thai capital Bangkok ahead of his announced return to Cambodia on Saturday.

The "acting president" of the Supreme Court-dissolved Cambodia National Rescue Party had said he would land at Bangkok’s Suvarnabhumi Airport on Friday on Thai Airways Flight TG931. He would then continue to Aranyaprathet on the border and into Cambodia through Poipet.

However, an agent at the Thai Airways counter turned him away, AFP reported.

"I am extremely shocked because the people need me in Cambodia," AFP quoted Rainsy as telling journalists. "I will never give up," Rainsy said as he got into a taxi to leave the airport, insisting he would seek "an alternative flight to be able to leave for Thailand today".

On Wednesday, while not mentioning Rainsy by name, Thai Prime Minister Prayuth Chan-o-Cha said the country would adhere to its “commitment to Asean" and "not allow any anti-government person to use Thailand for activism”.