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.

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.

"(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.

AFP