Rattan Mall was a young student at Delhi University in 1973, when Indira Gandhi, the last Indian prime minister to visit Canada, conducted a dazzling tour that seemed to signal a new era of co-operation between the two countries.

Instead of a breakthrough, however, the bilateral relationship cooled dramatically in 1974, when India violated an accord by testing a nuclear bomb using plutonium produced by a CANDU reactor, and the connection was further strained in 1985, when Canadian-based extremists bombed Air India Flight 182.

Forty-two years after Ms. Gandhi's tour, Mr. Mall and many other Indo-Canadians are wondering if the promise offered then will be realized now by the visit of Prime Minister Narendra Modi, a controversial Hindu nationalist whose right-wing Bhartiya Janata Party (BJP) swept to power in India last year.

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His visit is stirring emotions within the Indian diaspora in Canada, raising hopes of increased trade and a blossoming strategic partnership, but also aggravating old political tensions within the Indo-Canadian population, which numbers more than one million.

Indian immigration to Canada began early in the 20th century, and expanded starting in the 1980s, with settlement mostly in Toronto and Metro Vancouver, although several other cities also attracted large South Asian communities.

Mr. Mall, a veteran journalist and editor of the Indo-Canadian Voice in Vancouver, said he was shocked when he first heard Mr. Modi was coming to Canada and would stop not just in Ontario but also in British Columbia, where there is a history of Sikh extremism.

"I couldn't believe it. This is such a hotbed of Khalistan stuff, although that has kind of died out now," he said, referring to the movement to create an independent Sikh state in Punjab.

Mr. Mall said there is a great deal of excitement, but also deep concerns surrounding the visit of Mr. Modi, who was the chief minister in the state of Gujarat when riots erupted in 2002, leaving some 2,000 Muslims dead. Since the election, his pro-business policies have won praise, but his failure to speak out against the persecution of minorities in India has brought criticism.

So what do Indo-Canadians think of him?

"The mistake mainstream media guys make is that they think the South Asian community is one whole. But it's badly splintered, every which way," Mr. Mall said of the feelings about Mr. Modi. "He received like a hero's welcome in the U.S., in New York and in Australia, and he'll be getting the same reception in Toronto [where there is a large Hindu population] … but in Vancouver it's more tightly scripted, for obvious reasons. They are not sure what the situation is here."

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Kasi Rao, a member of the National Alliance of Indo-Canadians committee organizing Mr. Modi's appearance at Ricoh Coliseum in Toronto, where attendance has been limited to 8,000, said there is tremendous excitement about what many see as an historic event.

"The significance of this visit is this is truly a transformative visit in the Canada-India relationship," he said, predicting it will lead to increased economic and cultural linkages.

Mr. Rao said Mr. Modi has met in India with Canadian federal, provincial and municipal politicians in recent years and has a familiarity with this country that no Indian prime minister has ever had before. He is also leading the first majority government in decades and has a reputation for getting things done.

"And therefore the optimism the international business community feels for the prospect for reform is grounded in political reality," Mr. Rao said. He said optimism "resonates at an emotional level with the diaspora as well," and that explains why Mr. Modi's visit is generating such a buzz.

Vinay Sharma, vice-president of the Vedic Hindu Cultural Society, which is hosting a speech by Mr. Modi at the Laxmi Narayan mandir, a Hindu temple in Surrey, B.C., said they were overwhelmed with the response when people were asked to preregister for the event. The 5,000 tickets were taken in three days.

"Especially for the people of Indian origin, this is very important," he said of Mr. Modi's visit. "It will better the relationship between Canada and India, for sure. I can see that this is going to be a huge, huge transformation whatever is being done between Canada and India."

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Gurpreet Singh, a popular broadcaster on Spice Radio, agrees Mr. Modi will draw big crowds – but says not everyone will be a fan.

"He comes with that political baggage and there's a lot of anxiety in our community, especially among minorities in India," he said. "Ever since his government has come to power, minorities feel intimidated, especially the Muslims and Christians. So he's coming here and obviously there will be some protests… There are a lot of people coming together to show their anger and their dissent … we'll be seeing a lot of fireworks."

Mr. Singh said Mr. Modi will be able to win over some critics if he reduces a so-called blacklist that restricts travel to India by anyone suspected of links to extremism, if he takes steps to protect the rights of minorities in India, and if he acknowledges past atrocities against Sikhs.

Palbinder Kaur Shergill, a B.C. lawyer and legal counsel for the World Sikh Organization, said she hopes the visit will open a dialogue about more than trade.

"There was a recent spate of attacks against churches in the New Delhi area, and one of the church priests said there was not even an acknowledgement by the government that the attacks had occurred. So there is certainly a belief amongst many people that [Mr. Modi's] silence can be interpreted as acquiescence," she said. "What I'd like to see and what many others would like to see is for Prime Minister Stephen Harper to actually raise these concerns."

Aditya Tawatia, B.C. president of the Overseas Friends of BJP, said he hopes Mr. Modi's critics will set aside their differences and celebrate the visit for the economic opportunities it presents. "This is a very important moment for both countries," he said. "This is a big milestone, a turning point, a titanic shift in the relationship of both countries."

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Mr. Tawatia, whose organization supported the BJP election campaign in India and worked for years promoting a visit, was asked if it marks a breakthrough in the often wary relationship between the two countries. "Definitely it is," he said. "This is the time we've been waiting for."

Dave Hayer, a former Liberal MLA, said it is "very significant" that an Indian prime minister is visiting after a 42-year absence. "It's been too long," he said. "I think with that long gap both countries are equally at fault. We should have done a better job of keeping our relationship close."

B.C. Finance Minister Michael de Jong, who has made nine trips to India, sees Mr. Modi's visit as a sign that the importance Canada attaches to the bilateral relationship "is now being reciprocated." He said the trade opportunities for Canada in the huge India market are obvious, but if a new, more open and prosperous partnership is to develop, leaders in both countries will have to continue working long after the speeches and state dinner are over.

"There undoubtedly is excitement," Mr. de Jong said of the visit, "but here's the challenge we have to overcome, and I'll speak rather bluntly. The cultural ties between the countries are very, very strong, have been, continue to be. The challenge we both face is to convert that incredibly strong cultural link into a more powerful economic link."