As Prime Minister Justin Trudeau finishes his visit to China to try to deepen trade ties, the Liberals are sending a strong signal that they are open to rolling back the thresholds on foreign investment the Harper government set up in 2014.

"It’s something we would consider amongst a number of different things," David Lametti, parliamentary secretary to the Minister of International Trade, said on CTV's Question Period with Evan Solomon.

Lametti says Canada needs to rebuild a relationship with China, and then begin to focus on trade deals and “consider investment or the attempt to attract investment.”

After the Harper government approved the 2012 sale of the Calgary-based oilsands company Nexen to China’s state-owned enterprise China National Offshore Oil Corporation for $15 billion, they made an about-face by imposing tougher investment laws.

"When we say that Canada is open for business, we do not mean that Canada is for sale to foreign governments,” Harper said at the time. He argued that state-owned companies buying up Canadian companies were not a "net benefit" to Canada.

Now, after Chinese investment dried up and the price of oil collapsed, the Liberals appear open to reversing course. That has opposition members very concerned, especially as Trudeau is in China promising to deepen trade.

“Looking at that option seems to (bring up) the question of sovereignty again,” NDP MP Nathan Cullen said on Question Period. Cullen was also critical of the Liberals’ approach to discussing pipelines with China. “It almost seems like pipeline blackmail. If we want to have any trade with China, we might have to do something Canadian’s might not want.”

Lametti said the government has not formally explored this possibility of increasing the thresholds on foreign investment but would consider all proposals that might enhance trade.