The Federal Opposition says Communications Minister Stephen Conroy has been caught out using his influence to help a Labor figure win a plum government job.

Senator Conroy has confirmed he recommended former Queensland Labor MP Mike Kaiser for a senior role at the company set up to create the Government's National Broadband Network (NBN).

Yesterday a Senate estimates hearing was told the $450,000-a-year job was not advertised, and no other candidates were considered.

Mr Kaiser was a Queensland State Labor MP, but resigned in 2001 after admitting to being involved in vote-rigging during party ballots in the mid 1980s.

He is now running government relations for NBN Co, the company set up to build the Government's $43 billion National Broadband Network.

The company's chief executive, Mike Quigley, says Mr Kaiser was interviewed twice and his references were checked before he got the job.

Mr Quigley told the estimates hearing he was aware of Mr Kaiser's political past.

Opposition communications spokesman Tony Smith says Senator Conroy should not be arranging jobs for his Labor mates.

"Mr Kaiser is a very senior Labor figure, he has been on the scene for a long time," Mr Smith said.

"And for the minister to say, 'Oh well, off the top of my head, I think he could do the job' and for that position not to be advertised is not good enough at all.

"This is a position that pays more than the Prime Minister and that job should have been advertised.

"The minister's advice should have been: 'It's nothing to do with me. You should advertise, see who comes forward and make your own decisions'."

Mr Kaiser declined to comment on the furore over his appointment when asked by the ABC this morning.

Conroy hits back

Senator Conroy came under fire in the hearing but he hit back at Liberal Senator Nick Minchin.

"Senator Minchin, in the middle of the Telstra privatisation, interfered and had his good friend and spy John Short installed after he had been sacked, back in Telstra," Senator Conroy said.

"You had him installed after he had been terminated in a $60 billion company you were selling, Senator Minchin."

"That is nonsense and has got nothing to do with this case. To compare Mr Short to Mr Kaiser is ridiculous," Senator Minchin replied.

The clash continued when Senator Conroy later told the committee he still had not made up his mind on if he would publicly release a study into the viability of the National Broadband Network.

The government has previously been criticised for not conducting a full cost-benefit analysis.

"It may be possible for the report to be released, it may not," he said.

"But I will be in a better position to answer those sorts of questions after I've read the implementation study, which I have not yet received."