A boat carrying about 200 asylum seekers has capsized off the coast of Australia's remote Christmas Island, and authorities say it is likely many of them have drowned.

The vessel sank about 220 kilometers north of Christmas Island Thursday. Officials said 40 people spotted from an Australian military plane appeared to be standing on the ships's upturned hull.

Western Australia state police commissioner Karl O'Callaghan said initial reports suggest at least 75 people are believed to have drowned.

Australian maritime officials say Indonesia's search and rescue agency is assisting with the rescue efforts.

Australia is a major destination for people fleeing impoverished, war-torn countries such as Afghanistan, Iraq and Sri Lanka. Many of them are crammed into crowded detention centers on Christmas Island and the Australian mainland.

About 50 asylum seekers died when the leaking, wooden boat they were traveling struck the island's rocky cliffs in December 2010.