The Australian navy detained 54 suspected asylum seekers after intercepting their boat off the remote Northern Territory, officials said on Sunday.
Home Affairs Minister Bob Debus said a navy vessel spotted the boat last night off the Coburg Peninsula, northeast of Darwin.
Debus said they were being taken to an immigration detention centre at Christmas Island, an Australian territory in the Indian Ocean.
"The Australian government is committed to strong border security arrangements and is determined to deal effectively and appropriately with people smugglers," he said.
The Australian Broadcasting Corporation reported that most of the asylum seekers were believed to be from Afghanistan.
Last year, Australia announced a "more humane" policy towards refugees, scrapping a widely-criticised system which often resulted in asylum seekers, including children, being locked up for years.
It had already ended the "Pacific Solution", under which boat people were sent to special detention centres in the tiny island nation of Nauru or the Papua New Guinea island of Manus.