Australia's Maritime Rescue Authority is helping coordinate a rescue effort which is seeing commercial vessels help survivors, after a ferry sank with as many 350 on board along Papua New Guinea's east coast.
At around 15:00 AEST, around 28 people had been pulled from the water.
The MV Rabaul Queen went missing at about 8.30am (AEDT) when travelling between Lae and the West New Britain town of Kimbe on Thursday, PNG's National Maritime Safety Authority (NMSA) said.
By 17:30 AEST, the The Maritime Rescue Authoritysaid 219 survivors had been plucked from the water.
The Authority told SBS it has been helping coordinate the effort, broadcasting a request to ships in the area to assist in the rescue
"We've had a number of vessels respond...four of which have actively assisted", spokeswoman Carly Lusk said.
Ms Lusk said helicopters and aircraft were also helping, with a dedicated Maritime Rescue craft sent from Cairns, and Defence aircraft also sent in.
In PNG, rescue co-ordinator Captain Nurur Rahman confirmed four merchant ships were diverted to the scene by Australian authorities to help with the rescue.
Captain Rahman said he was being fed information from a NMSA agent on board one of the ships.
"The dynamics of this thing are changing all the time, minute by minute," he said.
Earlier, a NMSA spokesperson told AAP two helicopters from Lae have also joined the operation.
NMSA rescue co-ordinator Fred Siroi said he would make a public statement later in the day.
Australian diplomatic staff are monitoring the situation but there have so far been no reports of Australians on board.
Ship operator Star Ships could not be reached for comment.
Australian Prime Minister Julia Gillard says there is likely to be a very high loss of life.
"This is obviously a major tragedy," she said.
"We have been asked to provide assistance to PNG and we are providing assistance to PNG."
Ms Gillard did not elaborate on the assistance.
Australian officials were also working to ascertain whether there were any Australians on board, she said.
"But given the likely very high loss of life here I think when this news comes to the attention of Australians around the country they will be thinking about the people of PNG as they respond to this tragedy," she said.
