A Christmas Island resident says an asylum seeker boat has run aground on a remote beach and its passengers have be placed in immigration detention.

A group of 25 asylum seekers have been living unnoticed on a Christmas Island beach for days, according to locals, after their boat sunk off the coast.

Australian authorities including federal police, customs and immigration sprung into action on Thursday after part of the group were spotted walking up a rugged road from the isolated Dolly Beach on the island’s south east.

The group, believed to be Rohingya from Burma, had survived on crabs and coconuts since their boat came to grief on Monday, and were all uninjured, although slightly dehydrated.

Gordon Thomson, the island’s shire president, said the nine asylum seekers who walked to the road were taken into immigration detention.

The 16 who stayed behind on the remote beach later followed.

“The eight or nine who were taken away in the bus into detention had said that they had been on the beach since Monday, the boat had sunk and their friends were still down there,” Mr Thomson told AAP.

“They weren’t overly hungry or thirsty, even though they’d walked four, five, six kilometres from the remote Dolly Beach to the main road.

“They were in pretty good condition, so we expect that everybody else would be too.”

Mr Thomson said none of the asylum seekers had been injured or were unaccounted for after the boat sunk.

Fears a fatal accident may have occurred off the coast were raised after immigration minister Scott Morrison released a statement saying an incident of an “unconfirmed nature” had occurred and those involved were being questioned.

“Details of the incident are not clear at this point and persons who were involved in this incident are being questioned by on island agencies,” the statement said.

“On island agencies and Border Protection Command assets are also responding and are on scene.”

Information soon started flowing from those on the island.

The asylum seeker boat is one of four to have arrived in the past five days.

Mr Thomson said two vessels arrived overnight, while another carrying about 30 passengers was intercepted off Christmas Island on Sunday.

Greens’ immigration spokesperson Senator Sarah Hanson-Young said the fact more information was coming from locals than the government was an embarrassment.

“And reports from locals that the boat may have been drifting for some time raise questions about the capacity of search and rescue operations that have been thrown into chaos in recent weeks,” Senator Hanson-Young said.

“The government’s dangerous policies are not stopping the boats.”

Mr Thomson said asylum seekers were just trying to escape persecution and should be treated better.