NBN budget revised up again to $51 billion as higher costs and slower revenue bite

The peak budget for the completion of the National Broadband Network has been increased to $51 billion after higher costs of the rollout and deferred revenue. 

An additional $2 billion will be sourced from private investment markets to make up the shortfall, increasing the NBN's budget from the previous $49 billion. 

NBN Co chief executive Stephen Rue tells ABC's Peter Ryan that the rollout will be completed on schedule by 2020.