Earlier this month, the military said it would enforce a law allowing it to call up all men aged 18-35 and women aged 18-27 to serve for at least two years, as it struggles to quell opposition to its 2021 coup.

"While wounded and increasingly desperate, the Myanmar military junta remains extremely dangerous," the UN's Tom Andrews said in a statement.

"As the junta forces young men and women into the military ranks, it has doubled down on its attacks on civilians using stockpiles of powerful weapons."

The junta faces widespread armed opposition to its rule three years after seizing power from an elected civilian government and recently suffered a series of stunning losses to an armed alliance of ethnic minority groups.

Andrews said that with the conscription law, the junta was trying to justify and expand its pattern of forced recruitment.

In recent months, young men have reportedly been kidnapped from city streets or otherwise compelled into joining the military's ranks, he said.

"Young people are horrified by the possibility of being forced to participate in the junta's reign of terror. The numbers fleeing across borders to escape conscription will surely skyrocket."

Former US congressman Andrews is the special rapporteur on the situation of human rights in Myanmar.

Special rapporteurs are mandated by the UN Human Rights Council but are independent figures and do not speak for the United Nations.

Andrews deplored the "inaction" of the UN Security Council and urged countries to strengthen measures to reduce the junta's access to money and weapons.

He also called on the international community to increase humanitarian aid to the conflict-stricken country.

"Now, more than ever, the international community must act urgently to isolate the junta and protect the people of Myanmar."

The junta came to power in the February 2021 coup that ousted Aung San Suu Kyi's democratically elected government, ending a 10-year experiment with democracy and plunging the Southeast Asian nation into bloody turmoil.