The Shippers' Council says peak season surcharges on cargo bound for Australia could stifle exports.
The council believes shipping lines carrier ANL is the first to introduce the surcharges on westbound trans-Tasman cargo.
ANL will charge non-contracted cargo between $75 and $150 for each unit it ships from Auckland, Wellington and Tauranga for the peak season.
Council's chairman Greg Steed fears other carriers could follow suit, and says the added costs could stifle trade in products competing in the Australian market.
Export New Zealand says it's concerned the move will affect on small exporters which typically have no contracts with shipping lines.
ANL has refused to comment.