The boat carrying an unknown number of people was spotted by the crew of an oil tanker within Australia's offshore oil and gas fields 150 kilometres from the northwestern port of Dampier, Gary Kennedy, a manager of the oil and gas company Modec Australia, told The West Australian newspaper.
Kennedy did not immediately respond to The Associated Press's request for comment.
Border Protection Minister Peter Dutton's office refused to confirm the reports, saying in a statement: "We do not comment on operational matters."
But few boats, carrying mostly Middle Easterners and Central Asians from Indonesian ports, have come so close to the Australian mainland since the tough new stance was taken. Australian Broadcasting Corp cited an unnamed government source as saying the boat, understood to be carrying Vietnamese, will be intercepted by Australian authorities before it lands.
The asylum seekers would then likely be transferred to detention camps run by Australia on the Pacific island nations of Nauru or Papua New Guinea.