The incidents in Hamilton and Christchurch were understood to have been the result of the Sunday Star-Times commissioning people to masquerade as terrorists and gain access to restricted areas.
Police spokesman Jon Neilson said Police National Headquarters was aware of the incidents, but it was unlikely criminal action would be taken.
"We are aware of the situation and have been looking into it. But at this stage, it would not appear that there has been any offence committed," he told NZPA.
Mr Neilson said while police had a view on such behaviour, at this stage any comments about it were being left to Ms Collins. He said he didn't know how many people were involved.
Ms Collins said: "The actions are unbelievably stupid and irresponsible. This stunt had the potential to result in games being called off and stadiums evacuated."
Such action would have not only caused great public inconvenience and cost, but could have presented a risk to the safety of spectators.
"Common sense would tell you that running around a stadium dressed as a bomber has the potential to end very badly. If there had been panic there was the very real possibility that people -- particularly the elderly, children and those less mobile -- could have been hurt."
Ms Collins said the only outcome from people masquerading as bombers would be unnecessary increases in security being implemented at considerable cost and inconvenience to the public.
The Sunday Star-Times did not immediately comment on the issue.
