Once Were Warriors author owes creditors more than $3 million.

Christchurch developer Dave Henderson has failed to overturn a $2 million summary judgment over mortgage guarantees he provided for his mate Alan Duff.

High Court justice Christine French dismissed Mr Henderson's attempt to overturn the summary judgment.

She described his defence arguments as “implausible” and “nonsensical.”

Mr Henderson had claimed he was approached by Strategic in December 2007 over the arrangement. Strategic took over the property via mortgagee auction and nominated Mr Henderson’s company, Cleaver Factors, as the buyer.