It was Malcolm Turnbull's baby - albeit an adopted one - a 21st century network of wires criss-crossing the country, connecting Australia to its future at lightning speed.

And so, besieged by controversy though the National Broadband Network may be, the former communications minister fired up in defence of his pet project and his own conduct as he faced questions about police raids on Labor offices over damaging leaks.

"The AFP acts independently of government and so it should," the Prime Minister said, denying any prior knowledge of the matter, which the AFP says was referred to it by NBN Co in December.