Australian businessman Dick Smith says Australia must curb its population growth because the environment can't cope.
Australia is forecast to have a population of 36 million people by 2050 but Mr Smith says there won't be enough food and water for them.
The ABC reports he wants the government to cut the skilled immigration intake and encourage people to have fewer children.
"Politicians are completely letting the Australian public down," he said.
"Nine out of 10 Aussies don't want 40 million people here, but there's no discussion, there's no debate.
"There has to be, because what's the use of bringing kids in this world who even in a modern western country could starve to death, and that's what could happen."