West Australian grain handler CBH vowed to fight the "extremely disappointing" decision, which appears to be the latest trade strike fuelled by diplomatic tensions.

Chinese customs officials claim quarantine pests were found in CHB barley exports multiple times.

Attorney-General Christian Porter, who is from Western Australia, rubbished the allegations.

"I would think that whatever claims are now being made will turn out to be false, completely false," he told 6PR radio on Wednesday.

"When China, as they have a right to do, make claims of this type, we have to go through a process to disprove them, but I'm sure that they will be disproved."

Finance Minister Mathias Cormann said the federal government wanted to get to the bottom of the situation.

"We will be working with the company once we are aware of all the facts to make the appropriate representations," he told reporters in Canberra.

The grain cooperative insists there is no evidence to support the claim.

"CBH is therefore extremely disappointed the suspension has been put in place and will continue to work with the Australian government to challenge the suspension," the exporter said.

Australian farmers were already effectively blocked from exporting barley to China, which imposed tariffs of 80.5 per cent on the commodity in June.

Senator Cormann said CBH had a great track record, but declined to speculate if diplomatic issues had sparked the ban.

"The truth is, Australia's grain products, Australia's barley products, are highly regarded all around the world," he said.

"If there is less opportunity to export high-quality Australian grain into China there will be more opportunity to export grain into other markets around the world."

Labor leader Anthony Albanese said relations between Australia and China were through the floor.

"It's a real issue that Australian ministers can't pick up the phone and seem to have no relationship with their Chinese counterparts," he told ABC radio.

"China is the largest recipient of our exports, by a long way. It is a real concern that the Australian government don't seem to be able to manage the relationship."

China has also targeted Australian beef and wine after Prime Minister Scott Morrison led calls for an independent inquiry into the origins of coronavirus.

Mr Morrison announced a constitutional counterattack last week, signalling the Commonwealth would gain veto power over state government agreements with foreign nations.

The beefed-up powers would allow the foreign minister to pulp Victoria's Belt and Road Initiative agreement with Beijing.

Australian Associated Press