Search crews in Myanmar have recovered the bodies of about half of the 122 people who died in last week's military plane crash, the army has said.

Navy ships and fishing vessels have been battling strong monsoon swells to find victims after the Chinese-made Y8 aircraft carrying soldiers, family members and crew plunged into the Andaman Sea on Wednesday.

The number of bodies retrieved so far rose to 62 on Monday as the hunt for the plane stretched into the sixth day, the military said on its official Facebook page.

Nine children were among those found.

There has been no official explanation for the cause of the crash, one of several deadly incidents involving Myanmar military aircraft in recent years.

Heavy rains and rough seas have delayed rescue efforts [The Associated Press]

Army chief Min Aung Hlaing suggested weather was more likely to be a factor than mechanical failure.

He said on Sunday there was "a very big cloud" near the plane crash site, according to his official Facebook page. He did not elaborate. 

"The crashed plane was expected to be found soon as it crashed in the country's territory and some evidences were collected," he said.

But while monsoon season brings annual bouts of rainy weather, there were no reports of major storms along the plane's flight path when it disappeared while flying from the coastal city of Myeik to Myanmar's largest city, Yangon.

Myanmar authorities had rejected offers of help from several countries including China, the state-run newspaper Global New Light of Myanmar said on Sunday.

Some bodies pulled from the waters off Myanmar's southern coast were cremated last week as relatives and friends mourned the identified victims in the coastal town of Dawei.

The Y-8 plane was delivered to Myanmar in March last year and since had logged 809 flying hours.

The pilot and co-pilot both had more than 3,100 hours of flying experience and the plane was carrying about 2.4 tonnes of cargo, according to the military's Facebook page.

Source: News agencies