The Security Intelligence Service (SIS) issued 17 interception warrants in the 12 months to June last year covering phone tapping, listening devices and the taking and copying of documents, its annual report says.

"The information obtained materially contributed to the detection of activities prejudicial to security or produced foreign intelligence essential to security that was not likely to have been obtained by other means," director Warren Tucker said in the report, released today.

During the year under review 27 domestic interception warrants were in force - the 17 it issued during the period and 10 that were issued during the previous year which remained in force for some part of the period.

The report's only mention of counter espionage said "investigations were undertaken in a wide variety of contexts...instances have been detected of electronic attack against New Zealand's public and private sectors".

It said cyber attacks were a key new facet of national security work.

"Cyber techniques enable espionage to be conducted remotely and seek to exploit vulnerabilities in our systems that would be open not only to intelligence collection but also to other forms of attack."

The Government Communications Security Bureau (GCSB) also issued its annual report today, revealing even less than the SIS about its work.

"A number of foreign interception warrants...were in force during the year ended June 30, 2010," it said.

"A number of computer access authorisations were in force."

GCSB director Sir Bruce Ferguson said a review of the bureau's management structure had started "with a view to reducing the cost of management overheads and increasing the number of frontline positions".