Kim Aris, the son of Myanmar's deposed leader Aung San Suu Kyi, is demanding France's help to obtain independently verified proof of life for his 80-year-old mother.
Suu Kyi was moved to house arrest last Thursday on orders of junta chief Min Aung Hlaing, five years after he seized power in a 2021 coup.
Aris appealed directly to French President Emmanuel Macron in a letter handed to Foreign Minister Jean-Noel Barrot on Tuesday.
"We have had no proof of life, no photos for years, not even any indication that she was actually transferred. We still don't know where she is," said Suu Kyi's lawyer, Francois Zimeray.
The junta released an undated photo of Suu Kyi flanked by two uniformed men, but her legal team questions its authenticity.
"But we don't know if it's real or if it's AI," Zimeray said.
Another lawyer, Catalina de la Sota, expressed concern: "We cannot imagine that she is no longer alive, but why is she being kept in total secrecy, in violation of all international conventions? We are worried about her health."
The 2021 coup triggered a devastating civil war that has killed thousands and displaced millions across Myanmar.