Hundreds of containers of Australian table grapes are now backing up at ports in China for unconfirmed reasons.

Jeff Scott, chief executive of peak body the Australian Table Grape Association, told 9News the "abnormal" and "unforeseen" delays at multiple ports in southern China have been occurring for the past four weeks.

Australian grape exporters regularly ship between 200-250 containers to China each week, with China hoovering up 40 percent of Australia's total annual global grape exports, valued at A$630 million (US$485) million.

"It's abnormal," Scott said, confirming urgent discussions between exporters, the Australian government and China were underway to find out why Australian grapes were suddenly being held up.

"We don't expect to have delays this long," Scott said, admitting concern over frosty trade and diplomatic relations between Beijing and Canberra and the impact it could now be having on the industry.

"Normally, it takes maybe one to two days at the most to clear the fruit. We're hearing reports that it can take up to 10 - 15 days to clear the fruit arriving in China."

Chinese newspaper The Global Times last week reported Australian grapes were being subjected to special nucleic testing because of what it claimed was an "ongoing (coronavirus) epidemic" in Australia.

"This might be something new that the Chinese are imposing on fruit arrivals," Scott said of the nucleic tests.

"But as we know Australia is basically COVID free within the community. So I don't see [our grapes] posing any threat to the Chinese community at all."

Mr Scott said the delays at the ports would have serious financial knock-on effects for Australian exporters, who would likely be forced to cover the costs for unplanned refrigeration and storage of the grapes while they were jammed up at ports.

Any reduction in profit margins would be a real concern, he said.

Last week 9News.com.au reported Australia's $160 million hay exports to China were under threat, as dozens of Australian export permits had expired and had so far not been renewed by Chinese government officials.