The government says a new treaty with China is designed to address Canada's trade imbalance with the Asian economic powerhouse, but its chief critic argues it could undermine Canadian security and sovereignty instead.

The Canada-China treaty -- set for cabinet ratification this week -- aims to protect Canadian companies operating in China, as well as Chinese companies with operations here, from expropriation.

The deal also prohibits either government from treating companies run by the other's nationals any differently than domestic businesses.

Both Canada and China would also assume "most favoured nation" status, meaning they would have to make the benefits of whatever investment deals they sign with other countries available to one another.

But the most controversial of its terms is a provision calling for arbitration in the event investors feel they've been wronged. The three-member panel, made up of one arbiter from each of Canada and China as well as a third member of their choosing, would be able to hear the case in private before issuing a public ruling, including penalties to be paid by government.

For Green Party leader Elizabeth May, the deal is worrying, particularly in light of CSIS' security concerns about Chinese investment in Canada.

"I'm not an expert in security but I have to believe the people at CSIS are," May told CTV's Question Period Sunday, adding that her concerns don't stop there.

"This not only locks in investors from China with the ability to sue Canada, it also puts a positive obligation on the government of Canada to encourage investment from China into Canada and I think I’d like to hear from CSIS before we pass this treaty."

Furthermore, May said the deal undermines the rule of law, insofar as an independent judiciary usually ensures that.

But Minister of International Trade Ed Fast says the Canada-China deal doesn't do anything other international trade agreements haven't done in the past.

"In terms of the dispute resolution process, international arbitration is what we use in all of our free trade agreements," Fast told CTV's Question Period.

"This one is no different," he added, explaining that arbitration "provides a level of confidence that investors need."

And besides, Fast said, the agreement is "fully reciprocal."

May said, while that may be true, Chinese state-owned operations that might be interested in investing here dwarf their Canadian counterparts.

"If you look at Sinopec, the Chinese state-owned oil company, it’s the fifth-largest corporation on earth," she said.

"You don't have a private sector company seeking damages against Canada for something that they say was arbitrary under one of these investor state provisions. You've got the government of China telling the government of Canada that either federally or provincially or municipally, one level of government in Canada has done something which interferes with their expectation of profits."

In May's view, since the government unveiled the deal in the House of Commons on Sept. 26 and her motion requesting a debate was denied on Oct. 1, Canadians are not being given enough time to consider its implications.

Answering allegations the government is trying to speed this deal into law, Fast said the opposition parties failed to seize on earlier opportunities to debate it.

"We've provided full transparency in terms of tabling it under our tabling policy," he said, noting that the public has a 21-day window during which they can raise objections.

"We are absolutely confident this is an agreement that's in Canada's best interest and will drive economic growth and prosperity here at home."