Over 130 cyber-attacks were reported against critical infrastructure and Government targets in New Zealand in 2012.
The National Cyber Security Centre (NCSC) said attacks on government agencies and private sector industries and individuals who held critical information rose to 134 documented cases, up from 90 in 2011.
The NCSC is part of the Government Communications Security Bureau (GCSB).
GCSB Director Ian Fletcher said the attacks were "relatively small numbers", but "we are sure this is under reported".
About three-quarters of the incidents were attempts to gain information from critical industries or individuals who held critical information.
The most prevalent attack types were "scam or spam"-related attacks (fraud emails) followed by denial of service attacks (flooding websites) and botnet or malware attacks (secretly installing rogue programs).
Only two per cent were recorded as "successful network intrusion or compromise".
A NSCS spokesman would not disclose which organisations had been targeted for fear of follow-up attacks and to not alert the perpetrators.
More than half of the incidents originated overseas.