YANGON (REUTERS) - Myanmar's military authorities pledged on Monday (July 12) to ramp up oxygen supplies to help treat Covid-19 patients, as residents described their struggle to secure supplies to save loved ones from a record-setting wave of infections.

Photographs on social media showed long queues of residents in Myanmar's biggest city Yangon trying to refill oxygen cylinders.

In the city's Insein district, one resident reached by telephone said she had rented a cylinder and refilled it at the weekend after her father's oxygen level dropped. She was now desperate to get more.

"What if we can't find oxygen and... my father dies because of it," said the 24-year-old, who asked not to be identified.

Another resident said due to shortages of equipment some people were now using oxygen cylinders from the welding industry.

Ousted leader Aung San Suu Kyi was "gravely concerned" about the worsening coronavirus situation, her lawyer said on Monday.

Mr Khin Maung Zaw said Ms Suu Kyi voiced her concern during a meeting of her legal team before a court appearance.

Ms Suu Kyi has been detained since a Feb 1 coup and is on trial charged with multiple offences, which her lawyers reject.

A doctor who gives phone consultations to Covid-19 patients said he knew of many cases of people dying across Myanmar because they couldn't get oxygen in time.

Army spokesman Zaw Min Tun told a news conference on Monday that military authorities were preparing 14 locations for Covid-19 treatment in military hospitals across Myanmar.

He said oxygen plants would be operated at full capacity, while confirming media reports that sales to the public by some private providers had been restricted.

At the same news conference, a representative from the health ministry said oxygen supplies needed to be supervised in order to avoid hoarding.

"Some people may not have Covid-19, but store a large amount of oxygen tanks in their homes," said the official.

Myanmar is in the midst of its most serious wave of infections and on Sunday reported 3,461 new cases to bring its total to 192,213, while deaths rose 82 to 3,838.

Some health experts say the real rate of infection is likely to be far higher given a collapse in testing.

Health workers joined a civil disobedience movement to protest against the ousting of elected ruler Ms Suu Kyi, whose government had brought two previous waves of infection under control.