When an Air New Zealand jet to Shanghai was forced to turn around earlier this month, it seemed a relatively innocuous event put down to misfiled paperwork.

But it was the first of a string of incidents that are fueling concerns China may be turning a cold shoulder toward New Zealand after it barred Huawei Technologies Co. from its next-generation wireless networks. While Prime Minister Jacinda Ardern denies any friction, the opposition is calling on her government to shore up the relationship to avoid potentially dire economic consequences.

"Our relationship with China is worth over NZ$27 billion in two-way trade," opposition National Party foreign affairs spokesman Todd McClay wrote in a New Zealand Herald column on Sunday. "The prospect of a deteriorating relationship with China is a major risk. It hampers certainty in the economy and creates uncertainty for our exporters and tourism operators."