Security and vetting has been stepped up around Christchurch's inner-city cordon.
Two contractors were charged on Friday with breaching the inner-city cordon.
Civil Defence says the 54-year-old and 41-year-old men were acting suspiciously.
Their access to the area has been withdrawn and they will appear in court in May.
Police Superintendent Andy McGregor says there is now more scrutiny of people going to, and working within, the red zone cordon.
Mr McGregor will not release the details of the companies involved, saying the matter is before the courts.
