Chorus is looking into allegations of "improper behaviour" by some contractors connecting Kiwis to the ultra-fast broadband scheme.
Stuff reports that the company is investigating bribery allegations but a Chorus spokesman would not comment on the exact nature of the claims being probed.
The investigation covers more than just breaches of employment law, which surfaced in October after the Labour Inspectorate alleged nearly all broadband subcontractors it visited were breaching workplace standards.
Chorus, in a statement to the Herald this evening, said it had listened "carefully to a number of allegations made by some concerned technicians".
"Not all of the concerns raised relate directly to breaches of employment law, some relate to wider concerns questioning if the overall sub-contracting model is working as intended, and others allege improper behaviour by individuals," a Chorus spokesman said in the statement.
"We are following strict whistle blower protocols, including protecting the identity of the individuals who have raised the issues directly to us.
"A full and thorough process is being followed to ensure any response is fair, accurate and proportionate, as well as protecting the privacy of anyone implicated by the allegations until investigations are completed," the Chorus spokesman said.
NZX-listed Chorus, formerly an arm of Telecom, is rolling out the lion share of the Government's ultra-fast broadband scheme.
That project is installing fibre internet lines around 75 per cent of New Zealand and should be completed by 2020.
An array of contractors and sub-contractors are involved in the infrastructure build.
Chorus said this evening it was also working "constructively" with the Labour Inspectorate to identify any other "sub-contracted businesses who may be breaching employment law."
Chorus, in the wake of the Labour Inspectorate's sub-contractor allegations, has commissioned former deputy State Services Commissioner Doug Martin to conduct its own review.