Helen Clark's decision not to send troops to war has been vindicated by the United Kingdom's official inquiry, Labour leader Andrew Little says.

Speaking after the release of the highly critical Chilcot report on Britain's role in the Iraqi invasion, Mr Little said his party stood by its decision not to join the conflict in 2003.

At the time, Clark, as Prime Minister, said she did not believe that such a decision would be justified.

"The Chilcot report vindicates that view," Little said today.

Advertisement

"The lesson for us is that going to war should never be a gung-ho decision and should certainly never be made so New Zealand can be 'in the club' with its foreign allies.

"Little also said John Key was wrong to say that New Zealand was missing in action while he was in Opposition.

The Labour leader said the Iraqi invasion sparked regional instability and left a power vacuum filled by the Islamic State (Isis).