Suu Kyi, 75, faces a slew of charges since being overthrown by the army in a February 1 coup that cut short a decade of tentative democratic reforms and has plunged the Southeast Asian country into chaos.

"Daw Aung San Suu Kyi seemed not very well but throughout the hearing she seemed quite interested and paid keen attention," the head of her legal team, Khin Maung Zaw, said in a statement after the day of hearings.

Suu Kyi's supporters say the charges are politically motivated and designed to end the political life of a woman who championed democracy for decades under previous military administrations, much of the time under house arrest.

The Nobel Peace Prize laureate faced three cases on Monday at the specially built court in the capital Naypyidaw, where she had already appeared at preliminary hearings.

Two of Monday's cases were linked to the possession of the radios and one under the Natural Disaster Management Law for breaching coronavirus regulations while campaigning for the election she won last November.

She also faces charges of incitement - with hearings set for Tuesday - and more serious charges of violating the Official Secrets Act and under the Anti-Corruption Law.

Former President Win Myint also faces charges of violating the coronavirus measures. Police Major Myint Naing took the stand against him and Suu Kyi. Police Major Kyi Lin then testified in the cases over the radios.

Monday's hearings lasted more than five hours.

Her legal team have denied any wrongdoing by Suu Kyi and her chief lawyer, Khin Maung Zaw, called the most recent corruption charges "absurd".

Phil Robertson, Deputy Asia Director, Human Rights Watch, said in a statement the charges Suu Kyi faced "are bogus, and politically motivated" and "should be dropped, resulting in her immediate and unconditional release".

The army says it took power by force because Suu Kyi's party won the election through fraud, an accusation rejected by the previous election commission and international monitors.

Myanmar's security forces have killed at least 862 people during their crackdown on protests since the coup, according to the Assistance Association for Political Prisoners, an activist group, though the junta disputes the number.

Pro-democracy supporters took to the streets of the main city of Yangon on Monday, some chanting "revolutionary war, we participate", according to social media posts.

The United Nations High Commissioner for Human Rights Michelle Bachelet said on Friday that violence was intensifying and condemned the army's "outrageous" use of heavy weapons.

Bachelet said the junta had shown no willingness to implement a five-point consensus it agreed with the Association of Southeast Asian Nations (ASEAN) in April to halt violence and start dialogue with its opponents.

In a press release, Myanmar's junta-led ministry of foreign affairs rejected Bachelet's statement, questioning the accuracy and impartiality of the report.

"The report neither mentioned nor condemned the acts of sabotage and terrorism committed by the unlawful associations and terrorist groups as well as the sufferings and deaths of the security forces," it said.

The junta has branded a rival National Unity Government set up by supporters of Suu Kyi as a terrorist group and blamed it for bombings, arson and killings.

Australian Associated Press