Potatoes New Zealand chief executive Chris Claridge believed that was a major factor in the drop in export.
"We can see increased numbers of European fries into markets we normally supply, that's because they have to go somewhere," Claridge said.
"Europe traditionally exported about 400,000 metric tonnes of frozen fries and to put that into context, New Zealand's total annual exports is the equivalent of two weeks of European exports," he said.
"So they have the ability to swamp markets."
Claridge said the effects of Covid-19 on hospitality sectors around the world also affected the drop in exports.
Despite the drop in some market, Thailand showed plenty of interest in New Zealand potatoes in December, up more than 60 per cent on the same time in 2019.
Claridge said New Zealand had a good reputation for frozen fries and some buyers respected that.
"New Zealand frozen fries are of a world standard and generally buyers will stick with their existing suppliers and not swap out on the basis of price."
Claridge believed there was also dumping in the domestic market, and said that was why the industry took the matter to the Ministry of Business, Innovation and Employment for investigation.
That got under way in late October, and he said the ministry's work was progressing.
"Let me make it clear, as an industry, we absolutely support free trade but free trade doesn't mean no rules and we are looking to stabilise and secure our domestic market."
- RNZ