At least 38 people died after security forces tried to put down anti-coup protests in Myanmar on Wednesday, UN special envoy Christine Schraner Burgener said.

According to multiple reports from several cities and towns, police and military used live ammunition, as well as tear gas and rubber bullets, to quell protests in the deadliest day since demonstrations against February's coup broke out.

"Today it was the blackest day since the coup happened on the first of February. Today, 38 people died," Schraner Burgener said.

She said videos showing violence against journalists and the shooting of a protester were "very disturbing."

"It seems that the police used weapons like 9 mm submachine guns. So, live ammunition," Schraner Burgener said.

Schraner Burgener called on UN member states to employ all tools available "to stop this situation" and called for unity within the international community, a day after neighboring countries called for the government to use restraint.

"It's up to the member states to take the right measures," she said.

Fatalities in several cities

At least six people were shot dead in the city of Monywa in the country's Sagaing region, the Monywa Gazette reported.

The central city has turned out large anti-coup demonstrations in the past month.

Two demonstrators, reported to have been a 37-year-old man and a 19-year-old woman, were also killed in the second city of Mandalay.

At least one individual was killed and others injured in the central town of Myingyan, with reports of another fatality unconfirmed.

"They opened fire on us with live bullets. One was killed, he's young, a teenage boy, shot in the head," student activist Moe Myint Hein, who was wounded in the leg, told Reuters by telephone from  Myingyan.

In a statement, global NGO Save the Children said four children were among the dead, including a 14-year-old boy who was reportedly shot dead by a soldier on a passing convoy of military trucks. The soldiers loaded his body onto a truck and then fled the scene, according to the report.

Witnesses said at least eight people were killed in the main city Yangon.

"I heard so much continuous firing. I lay down on the ground, they shot a lot," protester Kaung Pyae Sone Tun, 23, told Reuters.

In the night, Yangon residents lit candles and held prayers for the victims.

Post-coup bloodshed 

Myanmar has faced chaos since February 1 when the military staged a coup and arrested de facto civilian leader Aung San Suu Kyi.

The coup brought to a halt Myanmar's decade-long experiment with more democratic governance and sparked daily mass protests.

The military regime in Myanmar on Tuesday said it had suspended its envoy to the United Nations, the Aung San Suu Kyi-appointed Kyaw Moe Tun. However, Tun has contradicted this, saying he should stay in post.

mvb, rc, jsi/msh (AFP, AP, Reuters, dpa)