The question is, just how many Ockers?

CANBERRA: Prime Minister Kevin Rudd has admitted he does not have any official advice on the ideal future population figure for Australia.

The nation's population ticked over 22 million in September last year, and is on a trajectory to reach 35.9 million by 2050.

Various groups are calling for a policy to ensure Australia's population growth is sustainable, but Rudd believes in the benefits of a "big Australia".

He told Fairfax Radio yesterday that he had not sought advice on Australia's ideal population, despite being asked the question "many times" in the past year.

"I don't have official advice before me as to what is, quote, an ideal population figure for Australia," he said. "I have simply taken the information provided to me as my predecessors have about where it's headed, and it's a slower growth rate for the next 40 years than it was for the last 40."

Rudd said the intake of migrants under his Government had remained about the same as it was under the previous, Howard, Government.

He said the challenge was how to prepare for the future population with infrastructure and services.

- AAP