The death toll from a ferry disaster on a river in central Myanmar four days ago has risen to nearly 50, officials said Wednesday, with most of the deceased identified as women and at least two dozen others still missing.

The overloaded vessel, whose passengers included scores of teachers and university students, went down early Saturday while it was travelling on the Chindwin River in Sagaing region.

Some 150 people were rescued alive on that day but officials believe the ship was carrying up to 250 passengers when it sank on its way to Monywa, a city around 72 kilometres (45 miles) south.

"We have found altogether 48 dead bodies so far," said local MP Tun Tun Win, a jump up from the 32 people pronounced dead on Monday.

"Many more could be dead," he said, adding that local monks have begun leading memorial services for the deceased.

An official from the local relief and resettlement department said two thirds of the dead were women.

At least 23 people -- 17 of whom are women -- are still missing, the official said, requesting anonymity.

One end of the brightly-painted ferry has been raised above the river's surface, with bloated bodies found trapped inside, but most of the vessel remains submerged.

On Wednesday rescuers continued efforts to raise the rest of the ship using cranes.