Police Minister Judith Collins is fuming at the "stupidity" of a Sunday Star-Times stunt that saw groups of people dressed as terrorist bombers - with fake bombs strapped to them - attend Super 14 games.

The newspaper commissioned people masquerading as terrorists to attend Super 14 Games at Waikato Stadium in Hamilton and AMI Stadium in Christchurch at the weekend, Ms Collins said.

"They gained access to public areas, the players tunnel and corporate hospitality areas and police attending the event were not advised of these activities," she said.

"This was incredibly stupid. If anybody had been discovered, then it is likely the games would have been called off. There could have been panic in the stadiums, people could well have been evacuated, and whenever you have a large crowd, people could have been injured.

"At a lot of these games there are children, elderly, people in wheelchairs. For the sake of a silly newspaper stunt, they have put other people at risk because of what would have happened if one of them had been discovered."

She said it was pure chance that they were not detected, and there was not an incident at the stadiums.

"They had fake bombs on them. It's very dangerous behaviour and so stupid it beggars belief. I find it hard to believe how any responsible newspaper editor would think that was a useful action to undertake for the sake of a story."

She did not know details of how many there were or what they were wearing, as police were advised by event organisers after the weekend.

She had a message for the Fairfax-owned Star-Times: "I'm asking them to act like adults and don't be so silly by putting people at risk."

Police spokesman Jon Neilson said police had been looking into whether there had been an offence committed.

"At this stage, in what we know, it doesn't appear any offence was committed.

"We've made our feelings known to the publication and we're leaving at that [for now]."

Since neither the venue nor police were alerted about the bomb threat stunt, police's anti-terrorism response was not involved, Mr Neilson said.

"We've had plenty of experience with other bomb threats ... This is different altogether."