Chorus is looking into allegations of "improper behaviour" by some contractors connecting Kiwis to the ultra-fast broadband scheme.
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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.