Kiwifruit marketer Zespri activated its emergency management plans after a sample of its fruit tested positive for Covid-19 in routine testing by Chinese officials.

China is the $3 billion global exporter's biggest market along with Japan. The greater China market returned $914m in FY21 for both New Zealand-grown and offshore-grown Zespri branded fruit.

A Zespri statement in response to Herald inquiries said test results for all fruit under investigation had since come back negative.

Zespri said it had recently learned that China's Market Supervision Authority and Centre for Disease Control in Yaohai District, Hefei City, Anhui Province, conducted routine Covid-19 testing of fruit in the wholesale market and "a sample of our kiwifruit tested positive".

"We are taking this matter extremely seriously, immediately launching our emergency management plans and co-operating with the relevant government agencies to trace the product shipment."

The New Zealand kiwifruit industry adhered to highest industry safety standards and to date there had been no reported cases of Covid in orchards or packhouses, Zespri said.

"The affected fruit from the Bay of Plenty was packed in May before being shipped from Tauranga on 16 August. There has been no reported community transmission in the region.

"The fruit was tested for Covid-19 upon arrival in China by China Customs and Zespri, as well as being disinfected, as per standard China Customs protocols.

"Since the beginning of the coronavirus epidemic, we have worked strictly in accordance with the requirements of the relevant national regulatory authorities and have co-operated with all the epidemic prevention and eradication work programmes for imported fruit and market distribution, to ensure that only the freshest, safest, high-quality Zespri kiwifruit reaches our consumers."

The Herald understands the sample of Zespri fruit was small.

The testing was part of routine screening of imported fruit.

Herald sources said Chinese regulators conducted a significant amount of testing of fruit, people and premises in relation to the customs batch - all returned negative.

Hefei City has had Covid cases in the past two months, sources said.

Zespri's local distributor also handles fruit from Vietnam and Thailand which have had Covid testing problems in the past, the Herald was told.

There is also the possibility there had been a technical testing problem.