The military's 2021 takeover prompted widespread public protests, whose violent suppression by security forces triggered an armed resistance that has now led to a state of civil war.
The son of Myanmar's ousted leader Aung San Suu Kyi demanded France's help in seeking independently verified proof of his mother's life on Tuesday after she was transferred to house arrest, her lawyers said.
The country's junta chief-turned-president Min Aung Hlaing ordered the 80-year-old Nobel Peace Prize winner to be moved on Thursday, five years after putting her into detention following a military coup in 2021.
But her son, Kim Aris, says he has still not heard from his mother, who remains massively popular inside Myanmar.
"I implore France to join my call so that we may obtain independently verified proof of life, and so that her fundamental rights are guaranteed: appropriate medical care, access to her lawyers and to her family," he wrote in a letter addressed to French President Emmanuel Macron.
Suu Kyi's lawyer, Francois Zimeray, said that Aris handed the letter to France's Foreign Minister Jean-Noël Barrot at a meeting 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," he told the AFP news agency.
The office of Min Aung Hlaing on Thursday shared an undated photograph appearing to show Suu Kyi sitting flanked by two men in uniform.
"But we don't know if it's real or if it's AI," Zimeray said.
Lawyer Catalina de la Sota, also representing Suu Kyi, added: "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."
During the meeting, Barrot said "France would continue to work for the immediate and unconditional release of Aung San Suu Kyi," the foreign ministry said.
The military's 2021 takeover prompted widespread public protests, whose violent suppression by security forces triggered an armed resistance that has now led to a state of civil war.
Ethnic minority militias and people’s defence forces that support Myanmar’s main opposition control large parts of the country, while the military holds much of central Myanmar and big cities including the capital, Naypyidaw.
The UN Human Rights Office said the military ramped up violence against civilians in 2024 to unprecedented levels, inflicting the heaviest civilian death toll since the army takeover as its grip on power eroded.
The Assistance Association for Political Prisoners, which keeps detailed tallies of arrests and casualties linked to the repression of the military government, said last year that at least 6,239 people had been killed and 28,444 arrested since the coup.
The actual death toll is likely to be much higher since the group does not generally include deaths on the side of the military government and cannot easily verify cases in remote areas.
Millions more have been displaced in the southeast Asian country of roughly 50 million.