The Rebels gang moved into Whangarei at Easter and set up a club in Porowini Avenue.
Building owner Noel Dyer says he was approached by two polite, clean-cut young men who told him they wanted to set up a gym in his empty warehouse.
He says there was no mention of the Rebels, and he agreed to let them have the building for three months.
Although Mr Dyer will not say whether he is evicting the Rebels, he does say the matter will be resolved in a couple of days.
A Rebels spokesperson says club members, including former New Zealand Tribesmen, are now drug-free and want to help local youths.