A boat carrying 63 people made it to the island yesterday before being detected by border protection officials.
A statement from Home Affairs Minister Brendan O'Connor says the boat was found "in the vicinity" of the island's Flying Fish Cove.
The boat is the second to be intercepted in as many days.
Yesterday, a boat carrying 53 people was intercepted 20 nautical miles off Christmas Island.
The island can house 1,400 asylum seekers and the latest arrivals put the detention centre over the limit.
The Federal Government has already drawn fire from the Opposition and The Greens after announcing it has 150 tents ready for detainees to use.
Another 200 beds in demountable housing will become available for use later this month.
- Australian Broadcasting Corporation
- © ABC