The country has been in turmoil since the military ousted Suu Kyi's elected government in February and embarked on a brutal crackdown on dissent that has killed more than 850 people, a monitoring group says.

Under house arrest and invisible bar a handful of court appearances, Suu Kyi has been hit with an eclectic raft of charges, including accepting illegal payments of gold and violating a colonial-era secrecy law.

On Tuesday, the court will hear testimony from witnesses claiming she broke coronavirus restrictions during last year's elections that her National League for Democracy (NLD) party won in a landslide.

A separate trial in which she is accused of sedition alongside ousted president Win Myint and another senior NLD member, is also scheduled to begin.

If convicted of all charges, Suu Kyi, 75, faces more than a decade in jail.

Journalists are barred from proceedings and there was a heavy security presence outside the special court in the capital Naypyidaw on Tuesday, an AFP reporter said.

The long-delayed hearings come as fighting flares in several communities across Myanmar and diplomatic efforts to resolve the crisis flounder.

Myanmar's ambassador to the United Nations, who has refused to leave his post despite being fired after the coup has called for the international community to take "effective collective measures" against the junta.

"The lack of such actions... will further encourage the military to continue committing inhumane and brutal acts against civilians," he wrote in comments published Monday ahead of expected UN Security Council talks on the Myanmar crisis.

Kyaw Moe Tun has passionately rejected the coup and brushed aside the junta's claims that he no longer represents Myanmar.

The United Nations still considers him as the rightful envoy.

Junta leader Min Aung Hlaing has justified his power grab by citing alleged electoral fraud in the November poll won by the NLD.

The junta has previously said it would hold fresh elections within two years, but has also threatened to dissolve the NLD.