Turnbull defends NBN's use of copper

Prime Minister Malcolm Turnbull has defended the national broadband network's purchase of 1800 kilometres of copper to deliver his vision of fibre to the node.

The company told a Senate estimates hearing it has so far purchased $14 million worth of copper and will need more to meet future demand.

Mr Turnbull told parliament on Wednesday the design of the NBN requires new copper to connect the nodes to existing Telstra pillars.

But the existing copper network between the nodes to premises has not required anything like the level of remediation that was assumed, he said.

If the government continued with Labor's policy of fibre to the home the project would have cost an extra $30 billion and taken six to eight years longer.

"We are getting on with the job. We are cleaning up your mess and building the network," Mr Turnbull said in response to questioning from the opposition.