SYDNEY (REUTERS) - Australia has stopped sending rock lobster to its biggest market of China after new Chinese customs inspections were imposed on the live seafood, an industry group and the Australian government said.

The new inspection delays come amid diplomatic tensions between the two nations, raising concerns in Australia that the live seafood trade will be the latest sector targeted for trade reprisals from Beijing.

Australia's agriculture minister David Littleproud said Australia had "serious concerns" about the inspections that began on Friday (Oct 30), and Australian officials were working to get clarification from Beijing.

The rock lobster is being checked for trace elements of minerals and metals, he told ABC television, adding that the seafood had already been tested before it left Australia.

He questioned "why this action is being taken against Australian rock lobster".

The Seafood Trade Advisory Group said on Sunday most Australian exporters had stopped sending lobster to China because of the risk of delays caused by the increased import inspections in China.

"Whilst some cargo has been cleared, there are continued risks of delays while new processes are being implemented," the group said in a statement.

"To mitigate this risk a decision has been made by the majority of exporters to stop sending shipments to China until more is known about the new process."

In 2018/19, China was the destination for about 94 per cent of Australia's A$752 million (S$721 million) in rock lobster exports, according to government data.

Mr Tom Cosentino, executive officer at exporter Southern Rocklobster Ltd, said he believed it was "a stretch too far to say this is related to any trade dispute".

"We will find out a lot more today about the new screening processes," he told Reuters.

China has been angered by Australia's call for an international inquiry into the origins of the coronavirus, and this year imposed dumping tariffs on Australian barley, suspended some beef imports, commenced a dumping investigation into Australian wine and changed conditions for Australian cotton.

Two sources familiar with the matter told Reuters China has rejected Australia's appeal to scrap the tariff on its barley exports, all but closing the door on a trade worth about A$1.5 billion in 2018.

"We were informed last week that the application was unsuccessful," said one Australian government source, who sought anonymity as he is not authorised to speak to the media. "We are extremely disappointed, but not surprised."

China's commerce ministry did not immediately reply to requests for comment.

Australia had requested the ministry in August for a formal review of its processes, following the imposition of the duties on barley. About 70 per cent of Australian exports of the grain typically go to China, Australian data show.

China concluded that Australia's Murray Darling Plan, a scheme to spruce up an ecologically vital river system, provided a subsidy for growers, although Australia denies it subsidises barley production.

Its rejection will force Australian farmers to sell barley to the domestic livestock industry at prices less than sales to China would have earned.

Australian barley production is expected to top 10 million tonnes after rain revived some of the biggest growing regions following years of drought.

Barley is typically used in breads and soups and dried to create malt for beer production, as well as being used for animal feed.