Myanmar's junta fired its United Nations ambassador Saturday for breaking ranks to denounce the military's ouster of civilian leader Aung San Suu Kyi, as police stepped up a crackdown on protesters across the country.

The country has been shaken by a wave of demonstrations since a coup toppled civilian leader Aung San Suu Kyi on February 1.

Authorities have ramped up the use of force to suppress dissent, deploying tear gas, water cannon and rubber bullets to disperse some protests. Live rounds have been used in isolated cases.

In justifying its seizure of power, the military has alleged widespread fraud in the November elections, which Suu Kyi's party won in a landslide, and promised fresh polls in a year.

Myanmar police moved in to break up an anti-coup protest in Yangon, using rubber bullets to disperse demonstrators
Myanmar police moved in to break up an anti-coup protest in Yangon, using rubber bullets to disperse demonstrators AFP / Ye Aung THU

But its ambassador to the United Nations on Friday broke ranks and made an emotional appeal to the international community for "the strongest possible action... to restore democracy".

Kyaw Moe Tun also pleaded with his "brothers and sisters" in Burmese to keep fighting.

"This revolution must win," he said, flashing the three-finger salute that has become a symbol of resistance against the junta.

By Saturday night, state-run TV announced that Kyaw Moe Tun was no longer Myanmar's UN ambassador.

Myanmar authorities have gradually ramped up the use of force to disperse protests against the military coup
Myanmar authorities have gradually ramped up the use of force to disperse protests against the military coup AFP / Ye Aung THU

"(He) didn't follow the order and direction by the state and betrayed the country," according to a MRTV broadcast.

"That is why he is revoked from his position starting from today."

News of Kyaw Moe Tun's removal follows a day of crackdowns and mass arrests by Myanmar's security forces as the country enters its fourth week of daily protests against the generals' grip on power.

Hundreds have been detained since the Myanmar military seized power on February 1
Hundreds have been detained since the Myanmar military seized power on February 1 AFP / Sai Aung Main

Chaos unfolded across commercial hub Yangon, with police closing in early on peaceful demonstrators and deploying rubber bullets to disperse them from Myaynigone junction.

Protesters scattered into residential streets and started building makeshift barricades out of stacked tables and trash cans to stop the police.

Many wore hard hats and gas masks, wielding homemade shields for protection.

"What are the police doing? They are protecting a crazy dictator," the protesters chanted angrily.

Myanmar has been shaken by a wave of protests across the country demanding a return to democracy
Myanmar has been shaken by a wave of protests across the country demanding a return to democracy AFP / Ye Aung THU

Local reporters broadcast the chaotic scenes live on Facebook, including the moments when the shots rang out, which AFP reporters on the ground also witnessed.

"We want to fight until we win," said protester Moe Moe, 23, who used a pseudonym.

At nearby Hledan junction several rounds of stun grenades were fired, according to AFP reporters.

At least three media workers were detained, including an Associated Press photographer, a video journalist from Myanmar Now, and a photographer from the Myanmar Pressphoto Agency.

Myanmar's ambassador to the United Nations Kyaw Moe Tun broke ranks to make an emotional plea to the international community to help end military rule in his country
Myanmar's ambassador to the United Nations Kyaw Moe Tun broke ranks to make an emotional plea to the international community to help end military rule in his country UNITED NATIONS / -

Another protest near a shopping centre in nearby Tamwe Township was broken up by police.

Aye Myint Kyi, a distraught mother of one shopper, said she reached her daughter briefly on the phone, who said she was being taken.

"I don't know where she was taken," she told AFP, crying. "She was unjustly arrested."

In the central city of Monywa, a rally had barely started before police and soldiers moved in on demonstrators, said a medic with a local emergency rescue team.

Htwe Aung Zin said his team had been "sent a man who was severely injured in his leg from the police crackdown", adding that they treated 10 others with minor injuries.

He declined to say what kind of bullets caused the man's injury.

Another medic -- who did not give their name -- told AFP that a woman with severe injuries had been sent to the intensive care unit.

Meanwhile, two local media outlets saw their journalists arrested as they attempted to broadcast live video of protests on Facebook.

Monywa Gazette's Kyaw Kyaw Win was beaten and arrested by plainclothes police, while Hakha Times' Pu Lalawmpuia was nabbed as he was filming authorities fanning out around him.

More than 770 people have been arrested, charged and sentenced since the putsch, according to the Assistance Association for Political Prisoners (AAPP) monitoring group, with some 680 still behind bars.

But Saturday is expected to push the number up, said AAPP's Bo Gyi.

"More than 400 were arrested (today)," he said, adding that only a fraction will make it into the group's daily updated list as they were not able to confirm the names of everyone.

Earlier in the day, MRTV also broadcast the arrival of more than 1,000 Myanmar nationals deported from Malaysia despite a court order halting the repatriation.

The migrants -- whom activists say include vulnerable asylum seekers -- received a hero's welcome at Yangon's navy port, attended by military families and officials.

Some of the returnees include ethnic minorities from Rakhine and Kachin state who may have "protection concerns", said John Quinley of Fortify Rights.

"The military has been on an all-out campaign to crack down on protesters, journalists, activists, and anyone calling for democracy," he said.

Since the coup, at least five people have been killed -- four of them from injuries sustained at anti-coup demonstrations that saw security forces open fire on protesters.

The military has said one police officer has died while attempting to quell a protest.