Supporters of Myanmar's military, some armed with knives and clubs, others firing catapults and throwing stones, attacked opponents of the Feb. 1 coup on Thursday, as protests against the new junta continued in the country's largest city.
Myanmar has been in turmoil since the army seized power and detained civilian government leader Aung San Suu Kyi and much of her party leadership after the military complained of fraud in a November election.
Protests and strikes have taken place daily for about three weeks, and students had planned to come out again in the commercial hub Yangon on Thursday.
But before many coup opponents congregated, about 1,000 supporters of the military turned up for a rally in the city centre.
Some threatened news photographers, media workers and witnesses said, and scuffles soon escalated into more serious violence in several parts of the city.
Several people were set upon and beaten by groups of men, some armed with knives, others firing catapults and hurling stones, witnesses said. At least two people were stabbed, video footage showed.
In one incident, several men, one wielding a large knife, attacked a man outside a city-centre hotel. Emergency workers helped the bloodied man after his attackers moved off but his condition was not known.
"Today's events show who the terrorists are. They're afraid of the people's action for democracy," activist Thin Zar Shun Lei Yi told Reuters.
"We'll continue our peaceful protests against dictatorship."
As dusk fell, dozens of riot police fired tear gas into a neighbourhood in the city to disperse a crowd that had gathered at an administrative office to protest the appointment of a local official by the junta, according to a witness and live-streamed video.
The violence will compound worries about a country largely paralysed by the protests and a civil disobedience campaign of strikes against the military.
Earlier, police blocked the gates of Yangon's main university campus, stopping hundreds of students inside from coming out to demonstrate.
Facebook said that due to the risks evident from the "deadly violence" seen since the coup it had banned the Myanmar military from using its Facebook and Instagram platforms.
The spokesman for the ruling military council did not respond to a telephone call seeking comment.
Military chief General Min Aung Hlaing says authorities are using minimal force. Nevertheless, three protesters and one policeman have been killed in violence.
'ABETTORS'
The United States, Britain and others have called for Suu Kyi's release and the restoration of democracy and have imposed limited sanctions aimed at members of the junta and its business links.
The British Foreign Office said on Thursday it would sanction a further six military figures, adding to 19 previously listed and including Min Aung Hlaing, and that the trade ministry would work to ensure British businesses do not deal with Myanmar's military-owned companies.
"Today's package of measures sends a clear message to the military regime in Myanmar that those responsible for human rights violations will be held to account, and the authorities must hand back control to a government elected by the people of Myanmar," Foreign Secretary Dominic Raab said in a statement.
A rights group said as of Wednesday 728 people had been arrested, charged or sentenced in relation to the pro-democracy protests.
The army said its overthrow of the government was within the constitution after its complaints of fraud in the Nov. 8 election, swept by Suu Kyi's party as expected, had been ignored. The election commission said the vote was fair.
The army has promised a new election after reviewing voter lists. It has not given a date but it imposed a one-year state of emergency when it seized power.
Suu Kyi has been detained incommunicado at her home in the capital Naypyitaw but her party says its November victory must be respected.
Veteran democracy activist Min Ko Naing said the military's efforts to arrange to an election re-run, which include a new election commission, had to be stopped and any parties involved in it were "abettors".
"We have to reject the actions of the military government to try to legitimise itself," he said in a post on Facebook.
The question of a new election is at the centre of a diplomatic effort by the Association of Southeast Asian Nations (ASEAN), of which Myanmar is a member, aimed at easing the crisis.
Indonesia has taken the lead in the attempt and its foreign minister, Retno Marsudi, met her military-appointed Myanmar counterpart, Wunna Maung Lwin, for talks in Thailand on Wednesday.
But Indonesia's intervention has raised suspicion among coup opponents who fear it will confer legitimacy on the junta and its bid to scrap the November vote and arrange a re-run.
Retno did not mention an election in comments to reporters after her talks but emphasised "an inclusive democratic transition process".
A Reuters report this week cited sources as saying Indonesia was proposing that ASEAN members send monitors to ensure the generals stick to their promise of fair elections, which would imply accepting the November result was void.
Protesters gathered outside the Thai embassy in Yangon on Thursday chanting "respect our vote".