An American tourist has been killed by a remote Indian tribe after he illegally ventured onto their island home.

John Allen Chau, 27, was met with a volley of arrows as he set foot on North Sentinel Island, part of the Andaman Islands deep in the Indian Ocean.

Police sources told local media that Mr Chau was a missionary and travelled to the island to convert the Sentinelese tribe to Christianity.

But police officer Dependra Pathak disputed this, telling local website News Minute the American "was on a misplaced adventure in (a) prohibited area to meet uncontacted persons".

Mr Pathak said authorities are still consulting with tribal welfare experts to determine how best to retrieve Mr Chau's body.

The case has cast a rare spotlight on the Sentinelese tribe, one of the last in the world thought to be untouched by modern civilisation.

Mr Chau was killed on November 16 when he paid local fishermen to transport him to the island, according to a police source.

"He was attacked by arrows but he continued walking. The fishermen saw the tribals tying a rope around his neck and dragging his body," the source said.

"They were scared and fled but returned next morning to find his body on the seashore."