New Zealand's KiwiRail has agreed shipping's first loan certified by the not-for-profit Climate Bonds Initiative organisation.

Law firm Holman Fenwick Willan said it had advised the group on the NZD 350m ($242m) pre- and post-delivery financing for two new ropaxes on order in South Korea.

The loan is provided by Westpac NZ, Societe Generale, Bank of America and National Australia Bank.