The Sunday Star-Times is standing by an investigation it ran involving sending reporters into Super 14 rugby matches last weekend carrying fake bombs.

The newspaper ran a series of stories today highlighting what it claimed were major lapses in security at an Eden Park cricket international, and rugby matches in Hamilton and Christchurch only 18 months out from New Zealand's hosting of the rugby World Cup.

Police Minister Judith Collins found out about the investigation during the week and slammed it as stupid and irresponsible.

It was ridiculous to expect Super 14 games to have terrorist-level security, and New Zealanders wouldn't want it, she said.

"I don't know what was going through their silly heads but I have to say that they put other people at risk and for that they should be very sorry," Ms Collins said.

Police investigated the breaches, and other than joining some rugby officials in backing Ms Collins' comments, said no charges were likely to be laid.

The newspaper said today reporters dressed as construction workers had managed to talk to players and access restricted areas with relative ease while carrying bags containing fake bombs.

It said the investigation was not a stunt, and Rugby World Cup security bosses and player representatives had expressed concern about how easy it appeared to be for the reporters to infiltrate restricted areas.

Ms Collins said the actions of the reporters presented a risk to spectator safety.

"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."

The Sunday-Star-Times said the story was done in the public interest and didn't accept people had been put at risk.

It said Ms Collins had "whipped up hysteria" before the story was published and made inaccurate accusations.

Stadium bosses have said security will be a lot tighter at the World Cup than it is at Super 14 matches, but don't want it to be stifling for spectators.