The gulf between what diplomats say in public and what they say behind closed doors has been laid bare by leaked cables between Washington and New Zealand.

The cables include a scathing American critique of New Zealand's attitude to the anti nuclear legislation and reveal efforts as recently as five years ago to get New Zealand to dump it.

Stuff.co say the cable, which appears to have been written by former United States ambassador Charles Swindells, would have caused a massive setback to US New Zealand relations if it had been made public when it was written in 2005.

It effectively labelled New Zealand a defence bludger, wrote off its peace keeping efforts as limited and grudging and said "even tiny Fiji" contributed "far more to support the US military capabilities around the world than does New Zealand".

But in public, the US was gushing in its praise of New Zealand's contribution in Afghanistan.

The cable was written in February 2005 as New Zealand troops served alongside US troops in Afghanistan and after big peacekeeping commitments in East Timor, the Solomons and elsewhere. New Zealand SAS soldiers received a presidential citation for bravery in Afghanistan.

The leaks also talks about New Zealand's "declining willingness and ability to work with the US", accuses NZ of refusing to pull its weight internationally and said its "practical contributions often fall short of the mark".

And it confirmed there was a financial payoff for New Zealand from sending engineers to Iraq.

The cable said sending combat engineers to Iraq has enabled the giant New Zealand dairy exporter, Fonterra, to bid on lucrative Iraq related contracts.

Story by: Vijay Narayan