THE opposition communications spokesman, Malcolm Turnbull, has a $10 million investment in an information technology company which, its managing director says, stands to reap ''new wealth'' from the Labor government's $43 billion national broadband network.

Mr Turnbull, who has been charged by Tony Abbott with demolishing Labor over the network, owns through two of his companies 5.4 million shares in Melbourne IT. Mr Turnbull's wife, Lucy, is a director.

The government is likely to try and use the shareholding to embarrass Mr Turnbull in this final week of Parliament as it seeks to get through the Senate a crucial bill for the network that will allow for the structural separation of Telstra.

Mr Turnbull hit back in advance yesterday, saying his critical approach to the network ''shows how uninfluenced I am by my personal holdings''.