About 3pm, police were called to help ambulance staff with the man, who was believed to be intoxicated, police said.
He was taken to Rotorua police station, where police custody staff became concerned for his welfare.
A police doctor, who was on site at the time, assessed the man and an ambulance was called. His condition deteriorated and police staff began CPR, police said. Resuscitation efforts continued until an ambulance arrived about 4pm, but he died before he could be taken to hospital.
In response to Rotorua Daily Post questions on how long it took the ambulance to arrive, whether the man was under constant supervision, how many others were in custody at the time, how many police staff were working and whether any interim measures had been put in place as a result of the death, Mrs Perks said it would be inappropriate to make further comment while the investigation was ongoing.
However, St John Lakes manager Hilary MorrishAllen said the ambulance arrived at the custody hub about three minutes after the call was made.
"The death in custody is in the hands of the IPCA and obviously St John will do an internal review, simply because of the nature of the incident."
A post-mortem examination was due to take place yesterday to determine what caused the man's death.
Police are also trying to confirm his last movements.
It is the first death in the Rotorua police custody centre since it opened in July, 2008.
The last death in custody in Rotorua was in May 2008, when Anthony McGuire was found dead in his cell.
