Wong must oversee NBN costs: Robb

The opposition is demanding federal Finance Minister Penny Wong take a more hands-on role to ensure the national broadband network (NBN) does not drain the public purse.

Opposition finance spokesman Andrew Robb has written to Senator Wong asking for more information to be made public on NBN Co's financial operations and cost control of the $35.9 billion project.

NBN Co is the government-owned enterprise charged with rolling out the wholesale broadband network.

Ms Wong should issue monthly financial statements for NBN Co in the same manner Australian government statements were released, Mr Robb said.

There should be updates of key financial activities, including equity injections, details of contracts awarded, other acquisitions, expenses and staffing levels.

Mr Robb said NBN Co had entered into contracts worth more than $7 billion with telecommunications and engineering firms such as Alcatel Lucent, Corning, Silcar and Ericsson amongst others.

But Senator Wong had not said whether the contracts represented value for money.

"What red-flag mechanisms are in place to alert Penny Wong to potential NBN Co activities that may not present best-value outcomes?" Mr Robb said in a statement.

"What veto authority does the shareholder minister have over decisions that are at odds with the interests of taxpayers?"

The minister's office said the government was committed to a high level of transparency and accountability for the NBN.

Mr Robb's assertion that there was no information, accountability or transparency was "simply unfounded", and Senator Wong would reply to Mr Robb's letter "in due course".

For the NBN, the government had expanded a framework for oversight of government business enterprises put in place by the Howard government, Senator Wong's office said.

"But we've also expanded this to further enhance transparency, given the significance of this investment in Australia's future."

NBN Co representatives had appeared before four parliamentary committees.

It had published reports, corporate plans and statements of expectations.

There had also being independent regulatory oversight by the competition regulator, and NBN Co was subject to investigation by the auditor-general and freedom-of-information requests.