Longer freight routes between the islands and through the northern South Island have prompted freight company Toll NZ to hike its rates.
This month's 7.8 earthquake near Kaikoura, which demolished State Highway 1 and the parallel rail link past Kaikoura, has resulted in a scramble by all freight movers to re-route freight by road and ship.
The inland Christchurch to Picton route is hundreds of kilometres longer and has been estimated by industry associations to add about 20 per cent to costs.
In a letter to customers obtained by the Otago Daily Times, Toll, New Zealand's largest domestic freight forwarder, said the company was incurring "considerable additional costs".
These were unavoidable, said Toll Group New Zealand's business development and sales general manager Roberto Brady.