"It is not surprising to me," Mr Key said of the increase. "If you look at the work we did ultimately about developing Cortex, that was a reflection of the fact that we think cyber security and cyber risk is the big risk actually that both the public service and the private sector now face, and we have been encouraging as best we can actually companies to think more about that."
Cortex is a cyber shield designed to protect government agencies and other organisations, such as power companies, from cyber attacks.
Its existence was first revealed by Mr Key before last year's election, ahead of Kim Dotcom's "moment of truth" event in Auckland, and in response to claims New Zealand had tapped the Southern Cross cable network.
What organisations are protected by Cortex is secret, but significant economic targets and vital network utilities are likely to be included.
The GCSB said theft of intellectual property or damage to IT systems was caused by malicious software (malware), that cannot always be countered with commercial tools.
Economic losses from cyber attacks are likely to be significant, including in the long term when valuable intellectual property is stolen.
Una Jagose, acting director of the GCSB, was set to reveal new details about the agency's activities, including Cortex, at a talk on Friday, but the public talk was called off after protesters refused to leave.
Both the domestic intelligence agency the SIS and GCSB, with its foreign intelligence mandate, have come under intense scrutiny after a series of revelations and allegations.
A wide-ranging review of both the SIS and GCSB, headed by former Deputy Prime Minister Sir Michael Cullen and lawyer Dame Patsy Reddy, is expected to report back by February next year.
