OTTAWA -- Canada has used a major World Trade Organization gathering to demand China deliver evidence that Canadian canola is contaminated.

Stephen de Boer, the Canadian ambassador to the world's leading trade body in Geneva, told the WTO's general council on Tuesday that Canada wants to meet in China in good faith to hear its science-based concerns that recent Canadian canola shipments were, in fact, tainted.

China banned shipments from two Canadian canola companies last month. This week, the government announced China had similarly banned pork from two Canadian companies.

"Open and predictable rules-based international trade is the only way global commerce can succeed. Co-operation between WTO members -- and willingness to engage on issues -- is equally important," de Boer said.

"Canada therefore concludes by asking again for China to provide the scientific evidence that supports its findings. This is a specific case, but I raise it in this setting because it's an important example of the broader concerns and the trend of increasing trade-restrictive measures."

De Boer's intervention at one of the WTO's most senior decision-making bodies is an attempt to push China, which has stonewalled requests for Canadian experts to travel to the People's Republic to examine Chinese evidence on the canola.

The government says two separate inspections by the Canadian Food Inspection Agency have turned up nothing, while several cabinet ministers have said China's complaint about the quality of the canola shipments is not science-based.

China's rejection of Canadian food products is part of the escalating tensions following the RCMP's December arrest in Vancouver of Huawei Technologies executive Meng Wanzhou. Canadian authorities detained her on a U.S. warrant alleging she committed fraud on American banks in an effort to get Huawei around sanctions against Iran.

Meng's arrest infuriated China. Nine days later, China imprisoned two Canadians -- ex-diplomat Michael Kovrig and entrepreneur Michael Spavor -- and accused them of violating China's national security. Both are still in custody.

While de Boer's statement is not the formal complaint that Conservative Leader Andrew Scheer has urged the government to launch, it represents the first formal opportunity to draw attention to the issue in front of a major meeting of the WTO, said a senior Canadian government official, who was not authorized to speak on the record because of the sensitivity of the situation.

China places great importance on being a member in good standing of the WTO, the world's trade referee, especially as it tries to displace the United States as a global trade leader.

De Boer told the WTO council that Canada wants to be a good trading partner and if another country sees a problem with a Canadian export, Canada wants to find a solution.

Canada has been working hard to resolve this issue with China, using every available means on the ground in both countries, said de Boer.

While Canada was pressing its case at the WTO, a Nova Scotia cabinet minister said the federal government would welcome American influence to resolve the ongoing dispute with China.

"I would say that it would be helpful, for sure," Rural Economic Development Minister Bernadette Jordan said in an interview. "It's different times now in the world than we've faced even four years ago. We see challenges all around the world. And we will continue, as a government, to stand up for our Canadian products."

Conservative MP Randy Hoback recently told the House of Commons agriculture committee he's concerned China might decide to single out Canadian maple syrup or seafood next.

Jordan said her constituency is the largest lobster-producing riding in the country, and hardly a day goes by without her talking to a fisher.

In 2017, Canada exported 10 million kilograms of live lobster to China.

Canada's efforts to diversify its markets for seafood continue apace with the ratification of free-trade deals with the European Union and the 10 Pacific Rim countries in the Comprehensive and Progressive Trans-Pacific Partnership, she said.

"Yes, China accounts for a significant portion of our lobster sales -- our seafood, it's not just lobsters. But I think with the ability for us to open up Europe, our ability to open up other Asian markets, there is that potential to make sure that those challenges are mitigated."

Jordan stressed there has been "absolutely no indication" of any movement by China to take trade action against Canadian seafood.

While she offered few details of what contingency plans the government may have if China does hit the seafood sector, Jordan suggested the government would come to its aid if necessary.

"We've worked with the canola farmers specifically on a package for them. I'm sure that when the time comes, if there's a need, we will be there for our fishers as well."

Last week, the government helped canola farmers by changing a special agricultural program that advances money against later crop sales. The change raises loan limits to $1 million from $400,000. The interest-free portion of that program is also rising to $500,000 from $100,000.

Agriculture Minister Marie-Claude Bibeau told The Canadian Press the government wants to ensure producers "have the support they need" and officials are "dealing with issues that arise on a case-by-case basis."