YANGON (AFP) - Mya Thwate Thwate Kaing was a teenage grocery store worker in Myanmar's sparse and isolated capital until less than two weeks ago, when a gunshot turned her into a national symbol of resistance.

The death of the young anti-coup protester has sent a ripple of grief through the country, days after a bullet struck her in the head during a confrontation with police.

She had joined a massive rally in Naypyidaw demanding the release and return to power of the country's ousted civilian leader Aung San Suu Kyi.

Police dispersed the protest with rubber bullets, but Mya Thwate Thwate Kaing was one of two people critically wounded by live rounds.

Her family marked her 20th birthday two days later while she lay unconscious on an intensive care hospital bed.

Hospital staff confirmed that she had died shortly before midday on Friday (Feb 19), 10 days after she was shot.

"We are heartbroken and cannot talk about it much now," her brother told AFP, adding that a funeral service would be held on Sunday.

Mya Thwate Thwate Kaing is the first confirmed death from the anti-coup movement since the military seized power on February 1.

Graphic video had circulated online of the long-haired teenager falling to the ground and onlookers scrambling to give her first aid.

Amnesty International says it has verified footage of the incident and that "police recklessly targeted protesters, with no respect for their lives or safety whatsoever".

Immediately after her shooting, Mya Thwate Thwate Kaing became a household name across Myanmar and a rallying point for a civil disobedience campaign against the new military regime.

A 15-metre-long banner with artwork depicting the moment she was shot was hung off a bridge in Yangon, while some protesters have carried photos of her as they march.

Mya Thwate Thwate Kaing's injury also brought scathing global condemnation of the junta.

"They can shoot a young woman but they can't steal the hope & resolve of a determined people," UN Special Rapporteur Tom Andrews tweeted.

The United States on Friday urged Myanmar's military to refrain from violence and relinquish power.

"We condemn any violence against the people of Burma and reiterate our calls on the Burmese military to refrain from violence against peaceful protesters," State Department spokesman Ned Price told reporters, using Myanmar's former name.

"The United States will continue to lead the diplomatic efforts to galvanise the international community into collective action against those responsible for this coup," he said.

Secretary of State Antony Blinken said that the United States, which has imposed its own targeted sanctions, hoped that international pressure would put the heat on the junta.

Mr Blinken addressed the crisis in separate joint calls on Thursday with Asian and European allies.

"Pressure takes time to be felt to be exerted," Mr Blinken told BBC World News.

"My hope is that as more and more countries come together in making clear that this is not acceptable," he said, "we will see a change from the military."

"The harsh reality is that the democratic transition has been interrupted," he said. "The international community needs to speak clearly with one voice that that is not acceptable."

'Hope for her future'

Mya Thwate Thwate Kaing's death sparked an outpouring of emotional tributes on social media as the news spread on Friday.

"We will regard you as our Martyr," wrote one supporter of the protest movement on Twitter. "We will bring justice for your loss."

A hospital official said the cause of her death would be investigated by a medical board.

The identity of the gunman remains unknown but Facebook and Twitter users have launched an online hunt.

Some have posted private details - including the home address and family business locations - of a man they suspect fired the bullet.

The target has denied the allegations and proclaimed his innocence in a Facebook post.

On her birthday last week, Mya Thwate Thwate Kaing's friends had taken flowers and food to a Buddhist temple to pray for her recovery.

"She was a young person who had much hope for her future," her sister Poh Poh told AFP at the time.

On Friday, residents in Yangon left flowers and messages outside a high court in tribute to Mya Thwate Thwate Kaing, with a black-and-white portrait of the young woman surrounded by Ms Suu Kyi's National League for Democracy flags.

"Blood should not be the currency for freedom," said posters strewn around the makeshift memorial.

Another said simply: "You will be remembered."