Private forest owners in New Zealand are thwarting government efforts to calculate carbon credits as a protest against the implementation of the Kyoto treaty.

Officials have reportedly been denied access to private forests in a “lockout” campaign by the Forest Owners Association, which says forest owners are not given carbon credits while other industries are not held responsible for their pollution.

Owners of forests planted before 1990 also face a liability if they do not replant harvested trees.

The switch from forestland to dairy farming is being blamed on unfair implementation of Kyoto.

The association said the dairy industry had managed to avoid paying a pollution tax.