"The authority has decided to investigate the full circumstances as it considers there is sufficient public interest for such an inquiry."
Its investigation would be based on four complaints it received in respect to both the alleged incident and the police investigation, he said.
It was not known how long this would take, he said.
DOC Central Otago operations manager Mike Tubbs said it investigated whether the men were illegally hunting on its land and concluded there was sufficient evidence an offence was committed, but the department would not seek to prosecute.
"Our decision to warn and not prosecute is based on a range of factors," he said.
These included the fact the men made early admissions and no animals were shot on conservation land.
DOC also took into account the men had not posed a danger to other members of the public and had no record of previous offending, he said.
"We take unlawful hunting seriously. In this case it was deemed the incident was at the low end of the scale and the likelihood of similar offending was extremely low.
"However, hunters are warned if they are found to be breaking the rules and putting people at risk the department will take action."
DOC urged hunters to ensure they had a valid permit before hunting conservation land, he said.
Federated Farmers laid one of the complaints to the IPCA, urging it to examine police handing of the alleged incident.
Its Otago president Phill Hunt said it welcomed the investigation.
"It is a good decision and we're past the first hurdle, that they believe there is something to investigate, but it doesn't mean the two officers involved will face charges."
There was a view among some farmers that if the men involved were not police, the case would have been handled differently, he said.
"We believe that there is one law for everyone, and there were a few things that weren't quite correct with the initial investigation of this case."
One reason the organisation decided to complain to the IPCA was because farmers wanted it to, he said.
"We have had members complaining about it, mainly those in Central Otago."
Federated Farmers Otago also wanted to support Central Otago police who had "done a fantastic job in the past on cracking down on poaching".
They were not involved in the case at all, he said.
"It is undermining some of the great work they've done in the past."
Poaching was a big problem throughout the whole provence, he said.
"It is theft and costs farmers many thousands of dollars worth of stock."
Regarding the DOC investigation, the department would "do what it would do", Mr Hunt said.
"Part of the reason we are against poaching on private farms is because the farmer could be held responsible if anything goes wrong on their land."
Police were unable to comment while the matter was under investigation by the IPCA, a spokeswoman said.
