Myanmar security forces surrounded the staff compound of striking railway workers opposed to the military junta on Wednesday as the UN failed to condemn the coup.
In New York, the UN Security Council called for restraint by the military and threatened to consider "further measures", despite not being able to agree on a statement that would have condemned the coup.
Talks on the statement would likely continue, diplomats said, after China, Russia, India and Vietnam all suggested amendments late on Tuesday to a British draft, including removal of the reference to a coup and the threat to consider further action.
The railway staff in Yangon are part of a civil disobedience movement that has crippled government business and included strikes at banks, factories and shops since the army ousted Aung San Suu Kyi's elected government in a coup on February 1.
Security forces have cracked down with increasing force on daily, nationwide protests, leaving the Southeast Asian nation in turmoil.
More than 60 protesters have been killed and 1,900 people have been arrested since the coup, the Assistance Association for Political Prisoners, an advocacy group, has said.
Footage posted on social media showed security forces near the railway staff compound.
In a Facebook live broadcast from the area people chanted: "Are we staff united? Yes, we are united" and a commentator claimed police were trying to remove barricades and threatening to shoot.
Details could not be independently verified. Police and army officials did not respond to requests for comment.
In Myanmar's second city, Mandalay, protesters staged a sit-in protest on Wednesday, chanting: "The resolution must prevail".
On Tuesday, Zaw Myat Linn, an official from Suu Kyi's National League for Democracy (NLD), died in custody after he was arrested, the second party figure to die in detention in two days.


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