Seventy-nine-year-old Myanmar politician U Win Htein has been sentenced to 20-years in jail for sedition, his lawyer said Friday.

Win Htein is a senior member of deposed national leader Aung San Suu Kyi's National League For Democracy party (NLD).

He was arrested in the aftermath of a February coup that plunged Myanmar into chaos.

“It's not a surprise but it's a sad and outrageous thing to hear about the ridiculous sentencing. Perpetrators of this injustice will be held accountable for this ... Please hold on people! We will win!” Win Htein's daughter, Chit Suu Win Htein, said in a message to Reuters:

First civilian politician to be jailed

Win Htein is the first high-ranking member of the NLD to be sentenced by the junta after a trial.

The former member of parliament is a longtime political prisoner, who has spent long stretches of time in and out of detention for campaigning against the military's previous rule (1962-2011).

Considered Suu Kyi's right-hand man, he was long been sought out by international and domestic media for insights into what Myanmar's de facto leader is thinking.

The wheelchair-bound politician requires oxygen to help him breathe, according to local media, and suffers from hypertension, diabetes, and heart and thyroid diseases.

His lawyer Myint Thwin told the AFP news agency that they would appeal the verdict.

Suu Kyi on trial

Suu Kyi too faces a raft of charges that could see her jailed for decades, from illegally importing walkie-talkies to flouting coronavirus rules.

She testified for the first time in a junta court on Tuesday, four months after being put on trial by the military, a source with knowledge of the case told AFP.

Media have been barred from attending Suu Kyi's trial at the special court in the military-built capital Naypyidaw and the junta recently banned her legal team from speaking to the media.

The military took power on February 1 sparking nationwide protests and a crackdown that has killed at least 1,100 people.

The junta said it returned because elections last year that returned Suu Kyi's party to office were flawed — an assertion the country's electoral commission has dismissed.

The coup prompted international condemnation and earlier this month, the Southeast Asian regional bloc ASEAN blocked Myanmar's junta leader from attending its summit.

Before she was deposed, Suu Kyi led a civilian government after her party swept a 2015 election, called when the military stepped back from half a century of direct rule.