The UN Human Rights Office says it has received “credible information” that a crackdown Sunday on anti-coup protesters in Myanmar has left at least 18 people dead and more than 30 wounded.

“Deaths reportedly occurred as a result of live ammunition fired into crowds in Yangon, Dawei, Mandalay, Myeik, Bago and Pokokku,” it said in a statement, referring to several cities in Myanmar.

“Tear gas was also reportedly used in various locations as well as flash-bang and stun grenades.”

“We strongly condemn the escalating violence against protests in Myanmar and call on the military to immediately halt the use of force against peaceful protesters,” its spokesman Ravina Shamdasani was quoted saying.

It would be the highest single-day death toll among protesters who are demanding that the elected government of Aung San Suu Kyi be restored to power after being ousted by a coup on February 1.

An Associated Press journalist was taken into police custody on Saturday while providing news coverage of the protests. The journalist, Thein Zaw, remains in police custody.

The Democratic Voice of Burma reported that as of 5pm in Myanmar, there had been 19 confirmed deaths in nine cities, with another 10 deaths unconfirmed.

The independent media company broadcasts on satellite and digital terrestrial television, as well as online.

Myanmar protests
Myanmar riot police with shields move forward during a protest in Mandalay (AP)

There were reports of gunfire as police in Yangon, the country’s biggest city, fired tear gas and water cannons while trying to clear the streets of demonstrators.

Photos of shell casings from live ammunition used in assault rifles were posted on social media.

Reports on social media identified by name one young man believed to have been killed in Yangon. His body was shown in photos and videos lying on a pavement until other protesters were able to carry him away.

A violent crackdown also occurred in Dawei, a much smaller city in south-eastern Myanmar, where local media reported that at least three people were killed during a protest march.

Photos posted on social media showed a wounded man in the care of medical personnel, and later laid out in a bed under a blanket with flowers placed on top.

Myanmar
Protesters shout slogans in Mandalay (AP)

Before Sunday, there had been eight confirmed reports of killings linked to the army’s takeover, according to the independent Assistance Association of Political Prisoners.

The coup reversed years of slow progress toward democracy after five decades of military rule.

Ms Suu Kyi’s National League for Democracy party would have been installed for a second five-year term in office, but the army blocked parliament from convening and detained her and president Win Myint, as well as other top members of Ms Suu Kyi’s government.

Sunday’s violence erupted in the early morning when medical students were marching in Yangon’s streets near the Hledan Centre junction, which has become the gathering point for protesters who then fan out to other parts of the city.

Videos and photos showed protesters running away as police charged at them, and residents setting up makeshift roadblocks to slow their advance.

Myanmar protests
People flash three-finger signs of resistance in Mandalay (AP)

Some protesters managed to throw tear gas cannisters back at police. Nearby, residents were pleading with police to release those they picked up from the street and shoved into police vans to be taken away. Dozens or more were believed to have been detained.

Sounds of gunfire could be heard in the streets of Yangon and there were what appeared to be smoke grenades thrown into the crowds.

“The Myanmar security forces’ clear escalation in use of lethal force in multiple towns and cities across the country in response to mostly peaceful anti-coup protesters is outrageous and unacceptable, and must be immediately halted,” said Phil Robertson, deputy Asia director for New York-based Human Rights Watch.

“Live ammunition should not be used to control or disperse protests and lethal force can only be used to protect life or prevent serious injury.”

“The world is watching the actions of the Myanmar military junta, and will hold them accountable,” he said.