YANGON, Oct 29 (AFP) - Myanmar's military junta sentenced a close aide of ousted civilian leader Aung San Suu Kyi to 20 years in prison for treason on Friday (Oct 29), his lawyer said.

Myanmar has been in turmoil since the military took power in a coup on Feb 1, with nationwide protests and more than 1,100 people killed by security forces, according to a local monitoring group.

"U Win Htein was sentenced to 20 years' imprisonment under section 124A by a special court," lawyer Myint Thwin told AFP, adding that they would appeal.

The former member of parliament is the first high-ranking member of Aung San Suu Kyi's National League for Democracy to be sentenced by the junta after a trial.

The 80-year-old is a longtime political prisoner, who has spent long stretches of time in and out of detention for campaigning against military rule.

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

Ahead of his arrest three days after the coup, he told local media that the military putsch was "not wise", and that its leaders "have taken (the country) in the wrong direction".

Aung San Suu Kyi faces a raft of charges that could see her jailed for decades, from illegally importing walkie-talkies to flouting COVID-19 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 Aung San Suu Kyi's trial at a special court in the military-built capital Naypyidaw, and the junta recently banned her legal team from speaking to the media.