Secrecy continues to shroud the advice the Government received on its decision to extend our defence force training mission in Iraq.

Documents obtained under the Official Information Act show certain New Zealand embassies and High Commissions were instructed to report on the views of key stakeholder governments about the Iraq mission.

All specific details in those reports are being withheld from public release.

Australian cabinet ministers are the only foreign politicians being named as having discussion with the New Zealand Government on its decision to extend our defence force training mission in Iraq.

Both Foreign Minister Murray McCully and Defence Minister Gerry Brownlee have confirmed they discussed the matter with their Australian counterparts.

In Mr McCully's case, his talks were held with Australia's Foreign Minister in mid-March - three months before the deployment extension was announced.

The Prime Minister's office confirms PM John Key discussed the matter with the Australian Prime Minister and other world leaders - but for the latter, his office says there are no formal records of them.

The Prime Ministers office confirms Mr Key was provided with information about the deployment by one of his intelligence directorates, the National Assessment Bureau.

However, their advice is also being kept secret.

Newly released papers on the Government's decision to extend our defence force training mission in Iraq are hinting at an involvement by one of the country's main spy agencies.

A briefing paper to help politicians and defence chiefs handle media questions on the deployment, reveals they were prepared to field questions about the GCSB and cyber capabilities being part of the deployment.

The notes make it clear no comment was to be made on GCSB operations, but that steps would be taken to ensure the security of the force's equipment and communications in Iraq.

And as for the GCSB and cyber strategies being used to support anti-ISIS operations - the notes say the purpose of the deployment was to build the capability of Iraqi security Forces, not engage in combat operations.

The papers also reveal the Government has considered sending SAS troops to Iraq, albeit in a limited role.

The Prime Minister ruled out in February, and again in June when the troop deployment to Iraq was extended, that the SAS would be deployed to Iraq in a combat role.

However papers released under the Official Information Act show that the SAS could be sent to provide advice on force protection and also to help with high level protection - such as they did with John Key's visit to Taji Air Base.