Why search for US missionary killed by remote tribe may be called off

Calls are growing to abandon a mission to rescue the body of a US man from an isolated island after he was killed by an "uncontacted tribe".

John Allen Chau was killed by bow and arrow when he journeyed onto North Sentinel Island in an attempt to convert the local tribe to Christianity.

It is believed his body was then buried in the sand.

The Sentinelese people are known for rejecting all contact with outsiders, and visitors are banned from the island due to concerns for the tribe's low immunity for common illnesses.

Survival International said this concern should be enough to bring a halt to efforts to recover Mr Chau's body.

Its director Stephen Corry said the operation poses significant threats - not only to the lives of rescuers, but to the entire population of Sentinelese people.

"The risk of a deadly epidemic of flu, measles, or other outside disease is very real and increases with every such contact," he said.

"Such efforts in similar cases in the past have ended with the Sentinelese attempting to defend their island by force."

In the 1800s, a British boat landed on North Sentinel Island in the hope of contacting the Sentinelese. It stumbled upon an elderly couple and two children, who they took "in the interest of science".

The elderly couple died of diseases contracted from the visitors, and the children were released back onto the island, the children likely passing on diseases when they returned home.

It is believed stories passed down from this time may have contributed to the Sentinelese's continued hostility.

Mr Corry said decisions to lift restrictions on visiting the island could be devastating.

"The weakening of the restrictions on visiting the islands must be revoked, and the exclusion zone around the island properly enforced."

Authorities issued a statement on Monday reiterating that the island remained off limits to foreigners as well as Indians, after some media reported relaxations of restrictions for visitors.