NBN Co executive chairman Ziggy Switkowski has refused to hand over an unredacted version of the national broadband network strategic review, citing confidentiality issues and ministerial advice.

At an NBN Senate Select Committee hearing at the NSW State Library on Tuesday, former Communications Minister Stephen Conroy requested that NBN Co table to the committee an unredacted version of the review.

NBN Co executive chairman Dr Ziggy Switkowski. Credit:Alex Ellinghausen

The review into the NBN Co and the rollout of Labor's fibre-to-the-premise network model was ordered by Communications Minister Malcolm Turnbull soon after the election. The review was delivered to Mr Turnbull on December 3. It was released publicly with redactions last week.

The motion to table the unredacted review was supported by Greens Senator Scott Ludlam and Labor Senator Deborah O'Neill.