Rescuers plucked more than 200 people from the sea off Papua New Guinea on Thursday after a ferry sank, leaving more than 100 missing and many feared dead, Australian authorities said.
This is obviously a major tragedy - 350 people on board a ship that has gone down, Australian Prime Minister Julia Gillard told reporters in Melbourne.
It is likely a very high loss of life here.
Australia's Maritime Safety Authority (AMSA) said 219 people had been rescued after eight vessels and three helicopters were diverted to the scene where MV Rabaul Queen went down early on Thursday.
AMSA spokeswoman Carly Lusk however said a greater loss of life may have been avoided as sea conditions were good, with a 10 knot (18kmh) wind and a light swell.
She said the ferry's owners had reported 350 people on board the 47m (155 ft) coastal ship.
We are getting more life rafts out into the water. There have been more reports of vessels sighting people in life rafts, so we're hoping for the number (of survivors) to increase in the very near future.
The ship reportedly sank about 9 nautical miles (16 kms) off Finschhafen on the South Pacific nation's north coast, on its way from Kimbe on the island of New Britain to the mainland city of Lae, AMSA said.
The ship's owners, Rabaul Shipping, said it had no information what caused the accident, adding the vessel sank quickly and without sending a distress message.
There is no sign of the Rabaul Queen, the company said in statement emailed to Reuters.
Papua New Guinea's maritime authority said earlier at least 28 people had been rescued, with many more floating in the sea near where the ferry went down.
Nurur Rahman, acting CEO of Papua New Guinea's maritime authority, said it was too early to speculate on the cause of the sinking.
AMSA said it received a satellite detection of a distress beacon belonging to the Rabaul Queen early on Thursday, and then alerted nearby ships to go to the scene.
An Australian search and rescue plane from the northeastern Australian city of Cairns, with multiple life rafts it can drop into the sea, had also arrived at the scene, while more planes were on the way from Australia, AMSA said.
Australian Foreign Minister Kevin Rudd said he has spoken to his Papua New Guinea counterpart to offer assistance.
Our hearts go out to those affected by the sinking, Rudd said in a statement.
Papua New Guinea, Australia's nearest neighbour, is largely undeveloped, with poor infrastructure and limited facilities despite enormous resources wealth.
The majority of Papua New Guinea's six million people eke out subsistence lifestyles in villages clinging to jungle-clad mountainsides or scattered around its many islands.
(Reporting by James Grubel in CANBERRA; Additional reporting by Lincoln Feast in SYDNEY and Maggie Lu in CANBERRA; Editing by Paul Tait and Ed Lane)