Communications Minister Stephen Conroy has kept mum in the face of burning questions on structural separation and regulation for the National Broadband Network (NBN).

Conroy on Tuesday took questions asked in a Senate Estimates hearing on notice, citing probity, and refused to discuss the NBN further than narrating tender documents.

He said doing so would undermine the RFP, and "risk inadvertent comment".

Liberal senator for South Australia Simon Birmingham criticised the minister for refusing to confirm whether the NBN will require structural separation.

"RFP appears to be open to structural separation [which] leaves open all manner of possibilities," Birmingham said.

"You have avoided scrutiny on the process. The government had every opportunity in the world to change the RFP [and] it's amazing you have shut down any discussion in the development stage.

"You seem to think the same ASX provision that applies to a public float would apply to the broadband tender. Every question is ruled out."

Structural separation is not a requirement of the RFP, however page nine of the tender document states that bidders with wholesale and retail operations should "demonstrate" what structures they have in place to avoid a network monopoly.

Conroy took questions on structural separation requirements on notice regarding statements earlier this month at the Sydney Institute where the minister said he would "carefully look at structural arrangements similar to those adopted in countries such as UK , NZ and Singapore" for the NBN.

"Anything more than opening statements I'll take it on notice," Conroy said.

The minister confirmed he consulted Finance and Deregulation minister Lindsay Tanner, the former broadband expert taskforce, and central department agencies regarding network separation, but refused to divulge discussions between the two.

Labor Senator for the ACT Kate Lundy attacked opposition statements that NBN proposals issued by the Tasmanian government would jeopardise the network,

"The Coalition has completely bungled it up and has egg on it's face," Lundy said, speaking in regards to a press release issued by shadow communications minister Bruce Billson.

The RFP considers NBN proposals submitted by states and territories, provided they meet network requirements and can contribute to coverage.

Shadow minister Billson said government has littered the NBN with gag clauses.

"This government has so far gagged a senate inquiry, gagged potential bidders from discussing it, gagged parliament from debating legislation relating to it and now in its latest attack against the parliamentary process has attempted to gag estimates," Billson said in a statement.