Mongrel Mob members were being monitored closely by Queensland police for an extended period before the gang was declared an "identified organisation'' this week.
Sources have told the Bulletin police had been in close contact with members in the southeast about their movements and expansion, including talking to them.
It is understood Queensland police have also been working closely with New Zealand authorities to identify members and get an understanding of how the gang works across the Tasman.
Assistant Commissioner Brian Wilkins said the declaration, made on Thursday by State Attorney-General Yvette D'Ath, would help police curb the gang's growth and potential criminal behaviour.
"We've been keeping a close eye on them for some time but they hadn't been a declared organisation," Mr Wilkins said.