"The country is dying under the control of Min Aung Hlaing, who never thinks about our people," protester Kyaw Thet in Yangon told dpa.
At the demonstrations, protesters chanted and called for justice, freedom and democracy in Myanmar. Many held banners bearing works by poet Khet Thi, who was arrested and killed by the military a few days ago.
"They shoot us in the head, but they don’t know the revolution is in our hearts,” Khet Thi had written.
Protesters have been marching across Myanmar in defiance of military rule for more than three months, ever since the elected civilian leaders were arrested and the country was thrown into political turmoil.
People were being forced to consider seeking safety outside the country, the UN Human Rights Office said on Tuesday, adding that they should receive such protection and support from Myanmar's neighbours.
"It is clear that there needs to be greater international involvement to prevent the human rights situation in Myanmar from deteriorating further," the UN office said.
It called on Asean to react quickly and to intensify its actions to ensure the military keeps to these commitments and to hold them accountable for failing to do so.
Meanwhile Thai police arrested three journalists from the Democratic Voice of Burma (DVB) who fled from Myanmar after they were ordered by the junta to stop reporting.
The three journalists were arrested Sunday in Chiang Mai along with two activists during a random search by Thai police. They have been charged with entering Thailand illegally, the DVB said in a statement.
The DVB called on the Thai authorities to be aware that the journalists' lives could be endangered if they were forced to return to Myanmar.
So far, the authorities in Myanmar have revoked the licenses of eight independent media outlets, a move affecting Mizzima, Myanmar Now, 7 Day, Khit Thit media, Democratic Voice of Burma (DVB), Myitkyina News Journal, The 74 media and Tachileik news agency. - dpa