At least 38 people were killed in Myanmar on Wednesday in what the UN described as the "bloodiest day" since the coup took place a month ago.

UN envoy to Myanmar Christine Schraner Burgener said there was shocking footage coming out of the country.

She also said it seemed likely security forces were shooting with live bullets.

Mass demonstrations and acts of civil disobedience have been taking place across Myanmar since the military seized control on 1 February.

Protesters have been calling for the release of elected government leaders, including Aung San Suu Kyi, who were overthrown and detained in the coup, and an end to military rule.

The latest violence comes a day after Myanmar's neighbours urged the military to exercise restraint.

'They just came out and started to shoot'

Ms Schraner Burgener said at least 50 people had now been killed "and many wounded" since the coup began.

She said one video clip showed police beating an unarmed volunteer medical crew. Another showed a protester being shot and very likely killed on the street, she said.

"I asked some weapons experts and they could verify to me, it's not clear but it seems that the police weapons like 9mm submachine guns, so live ammunition," she said.

Reports from inside Myanmar spoke of security forces opening fire on large crowds in a number of cities, including Yangon, with little warning.

Two boys, aged 14 and 17, were among those who were killed, Save the Children said. A 19-year-old woman was also said to be among the dead.

At least six people were reportedly shot dead during a protest in Monywa in central Myanmar. At least 30 others were wounded in the unrest, a local journalist told Reuters.

A volunteer medic told AFP news agency in Myingyan that at least 10 people had been injured there. "They fired tear gas, rubber bullets, and live rounds," they said.

"They didn't spray us with water cannon, [there was] no warning to disperse, they just fired their guns," one protester in the city told Reuters.

In Mandalay, a student protester told the BBC that demonstrators were killed near her house.

"I think around 10am or 10.30, police and soldiers came to that area and then they started to shoot at civilians. They didn't give any warning to the civilians.

"They just came out and they started to shoot. They used rubber bullets but they also used live bullets to kill civilians in a violent way."

The military has not commented on the reported deaths.

Military stands firm despite pressure

Ms Schraner Burgener has urged the UN to take "very strong measures" against the generals.

Pope Francis has called for dialogue to "prevail over repression". (BBC)

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