The country has been in an uproar since the military ousted civilian leader Aung San Suu Kyi on February 1, bringing an abrupt end to Myanmar's short-lived experiment with democracy.

The power grab triggered a massive uprising, which authorities have tried to quell by deploying lethal force and live ammunition.

As Myanmar entered its fourth month under military rule on Saturday, protesters in commercial hub Yangon -- an epicentre of unrest with a heavy security presence -- staged flash demonstrations, marching rapidly through the streets to avoid confrontation with police and soldiers.

"We have the truth. Only the truth will prevail," read a banner that protesters hoisted up as they marched quickly through a neighbourhood, flashing the three-finger salute of defiance.

In Yangon's Insein township, a bomb blast went off around 10 am near a local school, said a resident staying nearby.

"Some security forces came to check the blast area, but I only watched from a distance from my home because I was worried they would arrest me," he told AFP, adding that he saw smoke rising.

By afternoon, another two blasts went off in Yankin, further south, according to locals living in the leafy residential township.

"I heard it from my place, I thought it was thunder," a resident told AFP, adding that the explosions left the security forces nervous.

It remains unclear if anyone was injured by the blasts.

No one has claimed responsibility for the bombs -- which are exploding with increasing frequency in Yangon.

"They (the junta) have made people live in fear and it is good to have them on edge as well," the Yankin resident said.

He also praised the flash protesters for their ingenuity to evade arrest and crackdowns.

"Any show of defiance without getting captured or killed is great for the resistance."

Nearly 760 civilians have been killed in the anti-coup unrest, according to a local monitoring group, though the junta has recorded a far lower death toll.

Deposed leader Suu Kyi has been under house arrest since the military detained her on February 1.

The junta has hit her with a barrage of charges, including sedition and Myanmar's state secrets law.

Coup-maker Senior General Min Aung Hlaing has continuously justified the putsch as necessary to protect democracy, alleging fraud in November's election, which Suu Kyi's party won in a landslide.