Australia must slash its "breakneck" immigration rate by up to 50 per cent or risk tens of millions more people cramming onto the country's east coast, former Labor foreign minister Bob Carr says.
Australia's population ticked over to 24 million on Tuesday, on the back of record net overseas migration in the year to July 2015.
Mr Carr said the country's rapid population growth was flooding major cities and putting huge pressure on house prices.
"People wonder why their youngsters can't get housing in the big cities," he told reporters in Sydney.
"And the answer is we are going for breakneck population growth, and it's all about supply and demand."
The former NSW Labor premier and federal foreign minister said Australia's growth rate outstripped Indonesia's and was the highest of any developed country.
"We've got a third-world style population growth rate and I think the Australian people need to be alerted to this," he said.
"There's a case for pegging immigration back by easily a third, perhaps 50 per cent."
Up to 190,000 people will be admitted into the country this year under Australia's managed migration program.
There were 70,000 places offered through the program in 1999-2000.
Mr Carr said the "hugely over-ambitious" approach to migration was devised by Canberra bureaucrats without sufficient thought to the pressure it was putting on property markets and congestion in cities like Sydney and Melbourne.
"No matter how much governments spend on infrastructure, at this level of population, it's always never enough," he said.
"It's a nice idea to decentralise, but people come to the big cities.
"All of Australia's population growth will be settled in a narrow band along eastern Australia."
Mr Carr warned of future generations crammed into high-rise towers, which he said would lead to Australians "losing something of ourselves".
"Really the future is this: are we all in eastern Australia, in that coastal strip, going to be living in Hong Kong-style towers," he said.
"Because that's where we're going - that is the planning logic."
Mr Carr said Australia's population growth was bound to reach breaking point.
"There comes a point, given we've only got a narrow fertile coastal strip, when at 40 million, 50 million, 70 million by the end of the century, we've got to start thinking again," he said.
"This is not a model that continues indefinitely."
Mr Carr said capping population remained "perfectly compatible" with federal Labor's policy of running a high refugee intake.
Immigration Minister Peter Dutton's office declined to comment on Mr Carr's proposal.
