International Trade Minister Francois-Philippe Champagne says during a trip to China he plans to raise the case of two Canadian winery owners from British Columbia who have been held by Chinese authorities because of a customs dispute.

Champagne told reporters travelling with Prime Minister Justin Trudeau that he takes the case "very personally," and that he has raised it in the past with his counterpart, the Chinese commerce secretary, and will do so again on Monday in Beijing.

"We have voiced very clearly to the Chinese leadership our dissatisfaction and our concern," Champagne said.

"This is a matter that should not have led to the type of actions that was taken."

Amy Chang, 24, the daughter of John Chang and Allison Lu, told Trudeau in a letter this past week that the last 20 months have been a "nightmare" since her parents were jailed.

Trudeau en route to Beijing for a four-day state visit to China that will begin on Monday with a visit to a popular social media company to sell Canada as a vacation destination. Government officials say the focus of Trudeau's overseas trip will be deepening economic ties and attracting more Chinese investment to Canada, and that includes highlighting the upcoming 2018 Canada-China Year of Tourism.

But he is under pressure from human rights groups to raise consular cases with Chinese leadership.

Champagne said engaging economically with China allows Canada to have frank discussions about such cases.

Joined by several cabinet ministers, Trudeau is to arrive late Sunday, ahead of his Monday morning visit to the headquarters of Sino Corporation, which owns China's most popular social media platform, Weibo.

The prime minister is to take part in an event there to promote Canada as a tourism destination.

Weibo is billed as China's most popular social media platform, combining elements of Twitter, YouTube and Instagram. In September, Weibo's microblogging and social media services surpassed Twitter, and now reaches 376,000 monthly active users.

Trudeau departed for Beijing after attending a campaign event in Surrey, B.C. on Saturday in support of Liberal candidate Gordon Hogg, who is running in the Dec. 11 byelection.

The number of Chinese tourists visiting Canada more than tripled from 2010 to 2016 to 625,000 after China granted it approved destination status.

Later on Monday, the prime minister will meet with Premier Li Keqiang at Beijing's opulent Great Hall of the People, as part of an ongoing commitment to have yearly meetings with his Chinese counterparts. Trudeau's first visit to China was in the late summer of 2016.

Trudeau is to meet President Xi Jinping on Tuesday. He will also have meetings with senior Canadian and Chinese executives while in Beijing.

Despite China's eagerness to start free trade talks after several rounds of exploratory discussions, officials say Canada is still assessing its position.

The government recently released the results of consultations with more than 600 businesses, academics and civil society groups. Some surveyed said a pact with Canada could kill Canadian jobs and reduce the ability to compete against lax labour standards, lower environmental requirements and Chinese state subsidies.

In announcing the trip earlier this week, Trudeau's office made no mention of free trade, and government officials have said no decision has been made on whether to pursue such negotiations.

Champagne, Economic Development Minister Navdeep Bains and Bardish Chagger, small business and tourism minister, will accompany Trudeau for the duration of the trip.

Environment Minister Catherine McKenna is also headed to China, but she'll be with Trudeau only in Beijing, where she'll be promoting clean energy co-operation with her Chinese counterparts.

After Beijing, Trudeau is scheduled to move on to the city of Guangzhou where he'll give the keynote speech at a global business conference and meet with various business leaders about trade and investment.

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