Andy Teuber, former president of the Alaska Native Tribal Health Consortium, the largest tribal health organisation in the United States, disappeared while piloting a chopper on Tuesday afternoon from Anchorage.

A search was initiated later that day after he failed to reach his destination on Kodiak, in the western Gulf of Alaska.

Coast Guard helicopter and cutter crews scoured the waters northeast of Kodiak for a second day without finding conclusive signs of wreckage, and the search was called off.

Teuber, who was alone, was presumed to have perished in a crash.

"It's with a heavy heart that we have to suspend this search pending any new information," Coast Guard Commander Matthew Hobbie said in a statement.

"I offer my deepest condolences to those affected by this incident."

Material spotted in the water on Tuesday "was consistent with debris that would have been found on the overdue helicopter," though its connection to Teuber's chopper could not be confirmed, Hobbie said.

Teuber departed Anchorage the same day the Anchorage Daily News published a story detailing sexual misconduct allegations levied against him by a former employee.

The woman, according to the account, described a pattern of sexual coercion in a letter sent last week to ANTHC management.

Teuber denied the allegations, saying the relationship was consensual, the newspaper reported.

In addition to resigning from the tribal health consortium, which he led for over a decade, Teuber resigned his positions as a University of Alaska regent and as an Alaska Federation of Natives board member.

ANTHC is the nation's largest tribal health network with over 3000 employees serving 180,000 Alaskans, according to its website.

The Alaska Federation of Natives is the state's largest indigenous organisation.

Australian Associated Press