However, police confirmed they had found an explosive device, believed to be a grenade, when they were able to make a brief search of the house.
Northland police Inspector Kevin Burke said the Defence Force bomb disposal unit from Auckland arrived at the scene about midday yesterday to dispose of the grenade and check the house was safe before police could carry out a scene examination.
The bomb squad were expected to continue their search through the ashes today before police could begin their phase of the investigation.
The Fire Service was called and once the fire had been extinguished police were able to enter the house and found a man's body. Mrs Kennett said the man's name or age would not be released until next of kin had been notified.
Fire Safety investigators were working with police to establish the cause of the fire.
The Fire Service was called in by police about 12.30am yesterday, Muriwhenua area commander Allan Kerrisk said.
"When we got there the house and adjoining garage were fully involved . About 4.45am, when we were dampening down, we found what we think are human remains."
Kaitaia firefigther and Northland Fire Service volunteer support officer Colin Kitchen said a crew from Kohukohu was first on the scene, followed by a truck and tanker from Kaitaia.
Access to the burning building was a problem as the house was about 1km up a muddy track only accessible by four wheel drive vehicles. The track had been made nearly impassable by heavy rain and the number of vehicles using it earlier in the night.
Mr Kitchen said firefighters had to carry much of the gear in. A portable pump was used to pump 20,000 litres from a tank near the house.
"Really all we could do was dampen down the scene," Mr Kitchen said.
