China will likely instruct state-owned enterprises and private companies as early as Tuesday to halt imports of wheat from Australia - in yet another blow to Australia's exports.

Wheat will join a growing list of other goods from Australia banned from entering China's markets as the two countries' trade dispute continues.

Coal, copper, wine, sugar and barley from Australia are already barred. According to industry sources, China plans to include wheat on the list - but a date for the imposition hasn't been set.

The same sources say authorities might be sending out notifications Tuesday. The notices will include a warning to traders not to attempt to circumvent the policy by having shipments stop first in third countries.

"Chinese importers have been told to obey these rules strictly and suspend all orders for commercial reasons. Shipments arriving at the port before Friday will be released - but those arriving after will be impounded. It won't matter if they have already been sent to bonded areas," a trader who declined to be named said.

Last week, China authorities announced they would suspend further imports of products from Emerald Grain and timber from Queensland. Officials said the decision was made after inspectors allegedly found unacceptable levels of contaminants and discovered pests in some cargoes. The decision was preceded by similar trade restrictions on beef, anti-dumping duties on Australian barley and cheap Australian wine.

Bilateral relations between the two countries worsened in April after Australia sided with the U.S. over the launching of an international inquiry into the origins of the coronavirus pandemic.

The ban on Australian wheat is expected to undermine the country's grain exports to China - estimated to more than $843 million annually. Wheat accounts for nearly half of the country's total grain exports to China - or around $349 million.