* US push for 'intense' UN Security Council talks
* Protest begins in city of Yangon
* ASEAN to tell Myanmar it is 'appalled' - Singapore FM
* Anti-coup groups say ASEAN legitimising junta with meeting
Myanmar police opened fire to disperse protesters on Tuesday, witnesses said, as foreign ministers of neighbouring countries were due to hold talks with the military in a bid to quell violence and find a way out of the crisis.
The talks will come two days after the bloodiest day of unrest since the military removed Aung San Suu Kyi's elected government a month ago, unleashing anger and mass street protests across Myanmar.
Protesters, many wearing hard hats and clutching makeshift shields, had gathered behind barricades in different parts of the main city of Yangon to chant slogans against military rule.
"If we're oppressed, there will be explosion. If we're hit, we'll hit back," demonstrators chanted before police moved in firing stun grenades to scatter crowds in at least four different places in the city.
There were no reports of any injuries in Yangon but several people were wounded in the northwestern town of Kale when police fired live ammunition to disperse a crowd, according to a democracy activist and a reporter in the town.
"Several are injured, two are in critical condition," activist War War Pyone said.
Hospitals and police in the area could not be reached for comment. The military spokesmen did not answer telephone calls.
At least 21 protesters have been killed since the turmoil began. The army said one policemen was killed.
The coup on Feb. 1 halted Myanmar's tentative steps towards democracy after nearly 50 years of military rule, and has drawn condemnation and sanctions from the United States and other Western countries, and growing concern among its neighbours.
Singapore Foreign Minister Vivian Balakrishnan said his counterparts in the Association of Southeast Asian Nations (ASEAN) would be frank when they meet by video call on Tuesday and will tell a representative of Myanmar's military they are appalled by the violence.
In a television interview late on Monday, Balakrishnan said ASEAN would encourage dialogue between Suu Kyi and the junta.
"They need to talk, and we need to help bring them together," he said.
ASEAN groups Myanmar, Singapore, the Philippines, Indonesia, Thailand, Laos, Cambodia, Malaysia, Brunei and Vietnam.
The military justified the coup saying its complaints of fraud in a November election won by Suu Kyi's party were ignored. The election commission said the vote was fair.
Junta leader Senior General Min Aung Hlaing, in remarks read on state television by a newscaster, said protest leaders and "instigators" would be punished and threatened action against civil servants refusing to work.
Min Aung Hlaing has pledged to hold new elections and hand power to the winner but has given no time frame.
ASEAN's effort to engage with Myanmar's military has been criticised by supporters of democracy, with a committee of ousted Myanmar lawmakers declaring the junta a "terrorist" group and saying ASEAN's engagement will give it legitimacy.
Sa Sa, the committee's anointed envoy to the United Nations, said ASEAN should have no dealings with "this illegitimate military-led regime".
The alumni of ASEAN youth programmes in Myanmar said the bloc should be talking to the international representatives of Suu Kyi's administration, not to the regime.
"ASEAN must understand that the coup or the re-election promised by the military junta is utterly unacceptable to the people of Myanmar," it said it a letter to ASEAN.
Philippine Foreign Minister Teodoro Locsin indicated on Twitter that ASEAN would be firm with Myanmar and said the bloc's policy of non-interference in members' internal affairs "is not a blanket approval or tacit consent for wrong to be done there".
Suu Kyi, 75, appeared at a court hearing via video conferencing on Monday and looked in good health, one of her lawyers said. Two more charges were added to those filed against her after the coup, the lawyer said.
The Nobel Peace laureate has not been seen in public since her government was toppled and she was detained along with other party leaders.
Hundreds of people have been arrested since the coup, according to activists, the latest a journalist for the Democratic Voice of Burma, who live-streamed security forces outside his apartment on Monday in the coastal town of Myeik, where he had been filming protests. DVB confirmed the arrest.
The United States warned Myanmar's military on Monday that it would take more action if security forces kill unarmed people and attack journalists and activists, which State Department spokesman Ned Price called "abhorrent violence".
White House Press Secretary Jen Psaki said the Biden administration was preparing further costs on those responsible for the coup.
