Hundreds of people gathered solemnly on a beach in southern Myanmar on Thursday awaiting news of their loved ones as rescuers worked to pull bodies from the Andaman Sea after a military plane crashed with more than 120 people on board.

Navy ships and air force planes have been scouring the waves since late Wednesday afternoon, when the aircraft disappeared en route from the southern city of Myeik to the commercial hub of Yangon.

The commander-in-chief's office said 10 corpses, including five children, had been retrieved from the sea since a navy boat discovered wreckage from the plane early Thursday off the coastline near Dawei town. 

A local police source, who asked not to be named, put the tally closer to 20.

Hundreds of locals, relatives and NGO workers endured an agonising wait on the rain-battered San Hlan beach accompanied by stony-faced soldiers, as helicopters flew overhead heading towards military vessels just visible on the horizon. 

"My cousin's sister's family was in the plane crash -- her husband, her child and herself," Kyaw Swar Myint, 44, from Dawei, told AFP. 

"We heard news that the helicopter was now transporting about 20 dead bodies to the beach, so we are waiting here."

A military officer said the strong currents meant boats can not make shore, so many of the bodies may have to be airlifted to land. 

The Chinese-made Shaanxi Y8 plane was carrying a total of 122 people when it it disappeared on Wednesday afternoon during a routine flight, according to the latest military tally. 

More than half of the passengers were from military families, including 15 children, along with 35 soldiers and 14 crew members, the army chief's office said in a statement.

Some were travelling for medical check-ups or to attend school in Yangon. 

The office of State Counsellor Aung San Suu Kyi posted a statement expressing its condolences to the victims and pledged to support the rescue teams.

It is monsoon season in Myanmar, but there were no major storms reported along the aircraft's flight path on Wednesday afternoon.

- Poor safety record -

The military said the plane was flying at over 18,000 feet (5,486 metres) when it lost contact with air traffic control at 1:35 pm (07:05 GMT) on Wednesday, about half an hour after takeoff.

The military named the captain as "seasoned" pilot Lieutenant Colonel Nyein Chan, who it said had more than 3,000 hours of flying experience.

He was flying the Chinese-made four-engine turboprop, a medium-range transport aircraft based on the Soviet Antonov An-12, a widely used aircraft that has had numerous crashes over the decades.

Myanmar's former junta bought several Y8's during their 50 years of isolated rule, when they were squeezed by Western sanctions.

The military said the plane that crashed was delivered in March 2016 and had a total of 809 flying hours.

The debris was found in the Andaman Sea, north of the last known location of Malaysia Airlines flight 370.

That plane went missing in March 2014 en route from Kuala Lumpur to Beijing with 239 people on board, but no wreckage has ever been found. 

Myanmar's military fleet has a chequered recent history of plane crashes.

A former executive at the aviation ministry said many of the aircraft were old and decrepit.

"Myanmar air force has (a) very bad safety performance," he said, asking to remain nameless.

A five-strong crew died when an air force plane burst into flames soon after taking off from the capital Naypyidaw in February last year.

Three army officers were also killed in June when their Mi-2 helicopter crashed into a hillside and burst into flames in south-central Bago.

Source: AFP