Members of the Red Devils bikie gang were appearing in the Nelson District Court on Tuesday amid a strong police presence.
Police raided the gang's headquarters last Friday as part of an operation targeting organised crime in the region.
Police say the Red Devils gang is an offshoot of Hell's Angels and is not wanted in Nelson. All 11 members have been arrested.
At least 13 people were due to appear in court on charges ranging from participating in a criminal group and unlawful possession of fire arms and explosives, to manufacture and supply of methamphetamine.