More than 100 people are still missing after a ferry with over 350, many of them students, on board sank off the coast of Papua New Guinea on Thursday, even as rescuers managed to save over 200 from the choppy seas.
About 350 Papua New Guineans were on board the Rabaul Queen when it went down in the Solomon Sea about 8.30am Melbourne time, according to reports.
The ship was headed for the PNG north-coast town of Lae from the West New Britain town of Kimbe.
"Many on board were likely to be secondary students on their way to start the new school year," officials were quoted as saying by Australian daily The Age.
It said Australian rescuers saved more than 200 Papua New Guineans from drowning after the ferry sank, but by nightfall fears remained for more than 100 were still missing.
"About 200 people had been rescued - most of them from the water," Rescue co-ordinator Captain Nurur Rahman said, adding that several passengers were still unaccounted for.
Captain Rahman said four merchant ships were diverted to the scene by Australian authorities to help with the rescue.
The rescuers are scouring the area for further survivors, he said, adding the priority at the moment is to save lives.
He said it was too early to say why the ferry went down.
Operator Star Ships said it lost contact with the MV Rabaul Queen at about 6:00am (2000 GMT Wednesday) while it was travelling between Kimbe and Lae in the east of the Pacific nation, blaming bad weather for the disaster.
The Australian Maritime Safety Authority (AMSA) said the ferry, with about 350 people on board, went down 16 kilometres off the coast of Finschhafen, which is about 80 kilometres from its final destination of Lae.
Ferry operator Rabaul Shipping was quoted by the ABC news as saying it lost contact with the vessel early this morning.
Australian maritime authority put a call out for ships in the area to head to Finschhafen.
"We've sent three planes at this stage - one of them is already on scene, and that's one of AMSA's contracted dedicated search and rescue Dornier aircraft from Cairns," AMSA spokeswoman Carly Lusk said.
Earlier, Australian Prime Minister Julia Gillard said that the death toll could be very high.
"There has been a boat go down in Papua New Guinea with, as we understand it, 350 people on board," Gillard said.
"This is obviously a major tragedy... There is likely to be a very high death toll," she said.
Papua New Guinea Prime Minister Peter O'Neill has ordered a probe into the tragedy.