Suu Kyi's government was pushed out last year in a coup d'etat by Myanmar's powerful military, who alleged that she and her National League for Democracy party had committed electoral fraud in a 2020 poll.

The power seizure triggered widespread protests and dissent which the junta has sought to quell with a sweeping crackdown.

The 76-year-old Nobel laureate has been under house arrest since the Feb 1, 2021 coup, while members of her government have either been jailed or are currently in hiding.

Lawyer Yut Nu Aung was arrested in the second city of Mandalay on Wednesday and charged with financing terrorism, the source told AFP, requesting anonymity.

She had been representing former Mandalay chief minister and NLD stalwart Zaw Myint Maung, who -- like Suu Kyi -- is currently fighting corruption charges in a junta court.

Local media also reported the arrest and charge -- which carries a minimum sentence of 10 years and a maximum penalty of life in jail.

Yut Nu Aung will be held in court custody until May 12, the source added.

NLD lawmakers dominate a shadow "National Unity Government" that is working to overturn the coup and claims to be directing so-called "People's Defence Force" militia across the country.

The NUG and PDF groups have been declared "terrorists" by the junta, meaning it is illegal for anyone, including journalists, to contact them.

Suu Kyi's legal team have also been muzzled from talking to media since October.

On Wednesday a court in the capital Naypyidaw sentenced Suu Kyi to five years for taking a bribe of $600,000 cash and gold bars from a former Yangon chief minister.

Suu Kyi had already been jailed for six years for incitement against the military, breaching Covid-19 rules and breaking a telecommunications law -- although she will remain under house arrest while she fights other charges.

According to a local monitoring group, the junta's crackdown has left more than 1,700 civilians dead and seen some 13,000 arrested