At least six people were killed as Myanmar security forces fired on pro-democracy protesters Wednesday, after the junta hit half a dozen detained journalists, including an Associated Press photographer, with criminal charges.

Myanmar's military authorities have charged an Associated Press photographer and five other journalists over their coverage of anti-coup protests, their lawyer said Wednesday.

Ousted Myanmar civilian leader Aung San Suu Kyi was hit with two new criminal charges when she appeared in court via video link on Monday, a month after a military coup triggered relentless and massive protests.

Myanmar police fired rubber bullets to disperse protesters in Yangon on Saturday, after the country's ambassador to the United Nations broke ranks to make an emotional plea for action against the military junta.

Riot police in Myanmar on Friday dispersed hundreds of anti-coup protesters who have rallied daily in the country's largest city against a junta that toppled civilian leader Aung San Suu Kyi.

Nearly 140 NGOs from 31 countries signed an open letter Wednesday calling for the United Nations Security Council to urgently impose an arms embargo on Myanmar after the military coup there earlier this month. 

Indonesia said Wednesday it was in talks with both sides in Myanmar's political crisis and its foreign minister may visit to help find a solution, but she had no plans for an immediate trip.

UN chief Antonio Guterres on Monday spoke out against the "brutal force" used by those behind Myanmar's coup and urged the military to immediately halt the repression and release prisoners.

Tens of thousands of anti-coup protesters rallied across Myanmar again on Monday despite a clear threat from the junta that it was prepared to use lethal force to crush what it branded "anarchy".

Two people have died from gunshot wounds after security forces opened fire at protesters in Myanmar's second largest city on Saturday, emergency workers told AFP.