"The conviction of the State Counsellor following a sham trial in secretive proceedings before a military-controlled court is nothing but politically-motivated," Michelle Bachelet said in a statement.

"It is not only about arbitrary denial of her freedom -- it closes yet another door to political dialogue."

Suu Kyi, 76, has been detained since the generals staged a coup and ousted her government on February 1, ending the Southeast Asian country's brief period of democracy.

She has since been hit with a series of charges, including violating the official secrets act, corruption and electoral fraud, and she faces decades in jail if convicted on all counts.

On Monday Suu Kyi was sentenced to two years for incitement against the military and another two years for breaching a natural disaster law relating to Covid.

Former president Win Myint was also sentenced to four years on the same charges.

Last month, Than Naing, former planning minister of Kayin State, and Nan Khin Htwe Myint, former chief minister of Kayin State, were sentenced to 90 and 75 years behind bars on corruption charges, Bachelet pointed out.

"The military is attempting to instrumentalise the courts to remove all political opposition," she said.

"But these cases cannot provide a legal veneer to the illegitimacy of the coup and military rule."

The UN rights chief also strongly condemned the "vicious, utterly reprehensible" attack reported Sunday in Yangon, where soldiers rammed a car into a peaceful demonstrators and then opened fire using live ammunition.

Bachelet expressed concern that these developments risk further exacerbating tensions and violence.

Eyewitnesses said at least three people were wounded in Sunday's attack.

State media said one had sustained serious wounds and 11 had been arrested for protesting "without asking for permission".