Martin Lee was invited to give MPs on the House of Commons foreign affairs committee a briefing Tuesday on the democracy movement in Hong Kong.
The Chinese ambassador to Canada, however, has issued a letter to the committee telling it to butt out of China's domestic affairs, issuing a thinly veiled warning to not rock the boat on Sino-Canada relations.
Lee, the veteran pro-democracy activist, was one of several people arrested in December after more than two months of demonstrations against restrictions that Beijing government is imposing on Hong Kong's first election in 2017.
The protests paralyzed Hong Kong and gave rise to a new opposition movement that is seen by Chinese President Xi Jinping as a threat to his country's stability.
The Chinese government regularly sends toughly worded messages to democratic countries that entertain political figures that it does not approve of, such as the Tibetan spiritual leader, the Dalai Lama.
A letter from Chinese ambassador Luo Zhaojui said his government "learned" about plans to Lee to testify about political reform in Hong Kong on Tuesday.
"We hereby express our deep concern and strong opposition," the envoy's letter says.
"Hong Kong's political development falls entirely within China's domestic affairs. The Chinese side resolutely opposes any foreign governments, institutions and individuals to interfere in Hong Kong affairs," he adds.
"In consideration of the sensitive and complicated situation in Hong Kong, we hope that the Canadian side will not hold such a hearing, not intervene in Hong Kong's internal affairs in any form, so as not to send wrong signals to the outside world and cause any disturbance to China-Canada relations."
Luo refused to comment Monday when asked about his letter.
David Mulroney, Canada's ambassador to China until 2012, said Luo's letter reflects "an incomplete understanding" of how Parliament works.
"The ambassador needs to be aware of Canadian history," said Mulroney, the author of a new book on Canada-China relations.
"Canadians fought and died defending Hong Kong so we have a very special emotional connection — a blood connection to Hong Kong."
Canada has a moral responsibility as a "friend of Hong Kong" to speak out on its behalf, he added. "So it's actually incumbent on us to hear from people like Martin Lee."
The NDP's foreign affairs critic, Paul Dewar, said China should not see the appearance as provocative or unfriendly.
"This shouldn't be seen as interference. We see the relationship with China as being an important one. We have a very special relationship with China," said Dewar.
"As a friend, we think it's important we hear from people who are concerned about what's happening in Hong Kong," he added. "It's in no way to embarrass or to undermine the relationship."
Relations between China and Canada have been stormy since the Harper government took power in 2006.
Initially, Prime Minister Stephen Harper and cabinet ministers were outspoken about China's human rights record.
However, the Canada-China business lobby essentially revolted and managed to persuade the government to take a more nuanced view.
Harper eventually visited China in 2009, where he was publicly chided for taking too long to visit by China's then premier, and has since returned in an effort to boost trade. In all, he has visited the country three times, most recently last fall.
Harper has made increasing trade links with Asia a major economic priority, in part because of his inability to persuade the Obama administration to approve the Keystone XL pipeline that would allow oilsands crude to be pumped to the U.S. Gulf Coast.