The Government has secretly been sending intelligence operatives to take part in the war in Afghanistan.

The Herald has learned New Zealand's contribution to the war against the Taleban has included an "intelligence" component, separate from the military commitment.

Intelligence usually refers to the work done by spy agencies such as the Security Intelligence Service (SIS) and Government Security Communications Bureau (GCSB).

Prime Minister John Key, who is responsible for the agencies, refused to comment last night.

It is not known whose command the intelligence operatives are under, or what role they have been playing in the war.

Possibilities range from spying amid the Afghan community to high-end communications interception.

Their presence was revealed in a review of New Zealand's commitment to Afghanistan released under the Official Information Act yesterday.

The review lists intelligence as a contribution alongside the military, aid and police.

It also shows New Zealand is committed to two secret "non-military support roles", although details of the roles and how many operatives are involved have been removed because it would "prejudice the security or defence of New Zealand or the international relations of the Government of New Zealand".

The review also says personnel from six New Zealand Government agencies are involved in Afghanistan but lists only four: Foreign Affairs, Defence Force, police and NZAid.

The other two agencies with personnel there are kept secret for the same security reasons, making it likely they are the intelligence agencies.

Mr Key also revealed the intelligence agencies provided him with advice "about the security situation in Afghanistan", during a debate in Parliament yesterday. He said the advice helped him make the decision to send the SAS back there.

The intelligence agencies are both focused on domestic security so it is unusual for them to provide information about a foreign war zone.

The review shows the operatives were sent under the Labour Government. Labour leader Phil Goff, a former Defence and Foreign Affairs Minister, did not respond to the Herald last night.

The United States has called for improved intelligence for the military operations in Afghanistan, with President Barack Obama's chief intelligence adviser Dennis Blair saying the war effort lacks a deep understanding of the militants they are fighting.

There have been concerns that Pakistan's intelligence agents have been providing intelligence to the Taleban and there is a need to counter this.

A suicide attack last week killed the head of the National Directorate of Security, an Afghan agency equivalent to a combined CIA and FBI.