The Greater Sydney Commission’s Lucy Turnbull has been taken to task today after claiming Sydney is “far from full”.

Her claims follow a report which warned Sydney is behind similar global cities when it comes to congestion and commute times.

Australian entrepreneur and population control advocate Dick Smith is calling out her comments, challenging Mrs Turnbull to give an acceptable number.

“I put out a $5,000 challenge to any journalist who can get Lucy Turnbull to explain what her maximum or optimum number for Sydney is,” he tells Ben Fordham.

Dick Smith says a population boom is possible but would ruin life as we know it.

“You could have 20 million people in Sydney and destroy Sydney much like Shanghai.

“Noone will have a backyard, there won’t be any playing fields, you’ll have hundred-story tiny apartment blocks with our children living like termites, like battery chooks.

“It is possible to do if you’re that mad.”

Click PLAY below for the full interview