Relatives of scores of people missing after a ferry sank off Papua New Guinea's north coast vented their anger over a lack of information from authorities, Australian media reported Friday, as rescuers resumed their search.

At least 100 people are still missing and feared drowned after the MV Rabaul Queen, on its way from West New Britain to the mainland city of Lae, suddenly sank Thursday morning with about 350 people on board.

The first of 238 survivors plucked from the sea by rescuers began arriving in Lae on PNG's north coast early Friday, said Nurur Rahman, acting chief of Papua New Guinea's maritime authority.

As you would expect people who have been in the water for such a long time have a bit of dehydration, and they are very tired, Rahman told Reuters by telephone.

But police in West New Britain said relatives angry at the lack of information about their family members on the ship threw stones at the offices of the ferry operators, Rabaul Shipping, Australian Broadcasting Corporation Radio (ABC) reported.

There were a lot of people crying and then they wanted to know the fate of their loved ones, the people actually who were on board the Rabaul ship, Inspector Samson Siguyaru said.

Papua New Guinea Prime Minister Peter O'Neill has promised a full investigation into the tragedy.

The Australian Maritime Safety Authority said three merchant ships and four rescue aircraft were taking part in the search, near where the 47 metre (155 ft) ship sank about 9 nautical miles (16 km) off the South Pacific nation's north coast.

The ship's owners said they had no information about what caused the accident, adding the vessel sank quickly and without sending a distress message.

Rahman said there had been few signs of bodies in the water as searchers combed the area in difficult conditions with strong winds and high seas.

We have not sighted any fatalities, He said.

PNG, Australia's nearest neighbour, is largely undeveloped, with poor infrastructure and limited facilities despite enormous resources wealth.

The majority of its six million people live subsistence lives in villages clinging to jungle-clad mountains or scattered around its many islands. The island nation relies heavily on sea transport.

(Reporting by James Grubel; Editing by Paul Tait)