The men were part of a group of 12 seized on Tuesday as police launched a coordinated raid following months of careful monitoring of the group.
Aud Ingvild Slettemoen, who leads the environmental division of Norway's white collar police unit Økokrim, said that the men had been jailed for a week because investigators feared they would otherwise destroy evidence.
"It is because we believe there is a risk of that evidence relating to the work we are doing will be destroyed," he said.
A further four men could be incarcerated after a court hearing on Friday. The remaining six men have been freed.
The confiscated guns, laptop and tablet computers and phones, hoping to find evidence proving conspiracy to illegally hunt wolves.
Killing wolves is regarded as a serious crime in Norway and is theoretically punishable with a jail sentence.
Between 40 and 56 wolves were registered in Norway during the winter, putting the animal at risk of being wiped out in the country within just a few years.
According to VG, illegal hunters have killed as many as 100 wolves over the last decade.