People should not be alarmed by the large gap between the number of Australians - 3342 - registered as being in Japan at the time of last Friday's devastating earthquake and tsunami and the 2610 confirmed as safe, he said.
"It's simply a methodical process we go through to reduce this down one by one and it takes time," Mr Rudd told ABC Radio on Tuesday.
Of the 306 Australians known to be in the worst-affected areas, 128 have been confirmed as safe.
The Department of Foreign Affairs and Trade crisis centre has received 7653 calls from members of the public, concerned about family and friends.
Australia has sent a search and rescue team to Japan, and will provide any requested assistance, including victim identification teams and nuclear experts, Mr Rudd said.
