Since her ouster in a coup last year, Suu Kyi had been under house arrest at an undisclosed location in Naypyidaw, in Myanmar.
Ousted Myanmar leader Aung San Suu Kyi has been moved from house arrest to solitary confinement in a prison compound in the military-built capital Naypyidaw, a junta spokesman said.
Since her ouster in a coup last year, Suu Kyi had been under house arrest at an undisclosed location in Naypyidaw, accompanied by several domestic staff and her dog, according to sources with knowledge of the matter.
On Wednesday, she was transferred from house arrest to "solitary confinement in prison", junta spokesman Zaw Min Tun said in a statement.
Her future trial hearings would take place inside a newly-built courtroom inside the prison compound, he added.
A source with knowledge of the case said Suu Kyi's domestic staff and her dog had not accompanied her when she was moved on Wednesday, and that security around the prison compound was "tighter than before".
"Aung San Suu Kyi is in good health as far as we know," they added, speaking on condition of anonymity.
Since seizing power, Myanmar's military government has detained thousands of pro-democracy protesters, with many facing secret trials that rights groups have decried as politically motivated.
Suu Kyi's lawyers have been banned from speaking to the media, with journalists barred from her trial and the junta rebuffing requests by foreign diplomats to meet her.
"For the sake of the country and people, she (Suu Kyi) has sacrificed everything, but the wicked people are ungrateful and cruel," one social media user posted on Facebook following Thursday's announcement.
"What we are seeing is the Myanmar junta moving towards a much more punitive phase, towards Aung San Suu Kyi," said Phil Robertson, deputy Asia director for Human Rights Watch.
"They are obviously trying to intimidate her and her supporters."
Under a previous junta regime, Suu Kyi spent long spells under house arrest in her family mansion in Yangon, Myanmar's largest city.