The Defence Minister's promising any bad news out of the Iraq troop deployment won't be withheld from the public.

Most of the 143-strong contingent are now on the ground at Taji Airbase with the remainder expected to be in place in a matter of days.

Security around the deployment has been tight and official disclosures about the mission have been limited.

Defence Minister Gerry Brownlee argues they've tried to be as open as they can while maintaining a maximum level of security.

"But it's not our intention that we would try and mask any ill effect that might come from this."