Myanmar State Counsellor Aung San Suu Kyi's second court hearing on charges of possessing unregistered walkie-talkies began via video link in a Nay Pyi Taw court on Monday.

During the second hearing, a new charge was added to 75-year-old Suu Kyi in accordance with the country's criminal law, according to her legal team.

The country's president, U Win Myint, also returned to court on charges of violating COVID-19 regulations. 

The lawyer representing Suu Kyi, assigned by her party of National League for Democracy, said he has not yet obtained the power of attorney to participate in the trial.

Suu Kyi's lawyer Khin Maung Zaw told AFP that she appeared healthy during the court appearance, noting that she had not been seen in public since the military detainment on February 1.  

Suu Kyi is expected to be sentenced during this hearing. The maximum jail time for her charges are three years, according to the rules and regulations on import and export in the country.

Suu Kyi's first court hearing was on February 16, where another charge was added for violating a Natural Disaster Management Law.

Protesters marched in Myanmar on Monday in defiance of a crackdown by security forces that killed at least 18 people a day earlier, as calls grew for a more united international response after the worst violence since Myanmar military detained government leaders one month ago.

World leaders including UN Secretary-General Antonio Guterres strongly condemned the violent crackdown on Sunday. 

(China Media Group's Wang Yuezhou contributed to the story)