The Fianna Fáil leader says the government has serious questions to answer about the financing of the National Broadband Plan.
It's after key advisory reports overestimated the costs to the contractor by 1 billion euro.
The error was caught just weeks before the final bidder was given preferential status.
Fianna Fáil leader Micheál Martin says the revelations raise serious questions:
File image: Micheál Martin.