Suu Kyi was sentenced to "six years imprisonment under four anti-corruption charges", said the source, who requested anonymity because they are not authorised to speak to the media.
The 77-year-old leader was detained since the military staged a coup and toppled her government on February last year. Following this, she was hit with a series of charges like violating the official secrets act, corruption and electoral fraud. If found guilty of these charges the leader could face decades of jail-term.
Suu Kyi has already been sentenced to 11 years in jail for corruption, incitement against the military, breaching Covid-19 rules and breaking a telecommunications law.
Last year, in February, the coup sparked widespread protests and unrest which the military sought to crush by force. According to a local monitoring group, the crackdown has left more than 2,000 civilians dead and seen some 17,000 arrested.
For the last 30 years, Suu Kyi has been the face of democracy in Myanmar. But her six-year sentence already meant she is likely to miss elections the junta says it plans to hold by next year.
In June, she was transferred from house arrest to a prison in the capital Naypyidaw, where her trial continues in a courthouse inside the prison compound.
She remains confined to jail in the capital, with her link to the outside world limited to brief pre-trial meetings with lawyers.
Many of her political allies have also been arrested since the coup, with one chief minister sentenced to 75 years in jail.
Last month, the junta stoked renewed international condemnation when it executed Phyo Zeya Thaw, a former lawmaker from her National League for Democracy (NLD) party for offences under anti-terrorism laws.
Suu Kyi learned of the execution at a pre-trial hearing, a source with knowledge of the matter said, but has yet to speak on the matter.
