Foreign ministry officials in Paris have warned their counterparts in Phnom Penh not to take any action without a solid basis after a French architect with ties to disgraced politician Bo Xilai was arrested in Cambodia this week.
In seeking reasons for Patrick Devillers' arrest, a spokesman said, "we've made it clear that we'll be watchful that no legal action of any kind is brought against him unless its legal basis has been clearly established."
The arrest came as a new twist in China's biggest political scandal in China in decades.
Cambodia said the arrest came with backing from Beijing, which seeks Devillers' extradition.
He is said to have been a business associate and friend of Bo, 62, who was chief of Chongqing, and wife Gu Kailai, 53.
Bo is being probed for corruption while Gu has been detained for suspected involvement in the murder of British businessman Neil Heywood last year.
The scandal broke in February and exposed divisions within the Communist Party before the upcoming leadership transition. AGENCE FRANCE-PRESSE