Improving trade relations with India and China will ensure the "doors of opportunity are open for Canadian businesses," Trade Minister Stockwell Day said Sunday, ahead of Prime Minister Stephen Harper's first trips to the two emerging economic powers.

Day told CTV's Question Period that diversifying Canada's economy is a top priority, which will help Canada weather trade slowdowns that come with economic downturns, as is the case with the United States, Canada's largest trading partner.

"Diversification is something that has been happening, and needs to continue to happen," Day said from Singapore, where he was attending the Asia-Pacific Economic Co-operation summit.

"We want to make sure...that if a market weakens, even in a temporary way as it has with the U.S., we want to make sure that for Canadian business the tax load is as light as possible, the regulatory regime is common sense and we level the playing field with trade deals with other countries so that Canadian producers and investors aren't at a disadvantage."

Harper arrived in India late Sunday after attending the APEC talks. He will return to Canada for a couple of weeks before he visits China from Dec. 2 to 6.

The prime minister will spend three days in India, where he is expected to press Canadian nuclear technology, as well as infrastructure and energy expertise.

According to Day, India will need 25 to 35 nuclear reactors in the next 20 years, and officials there "are very open to Canadian nuclear technology."

Canadian officials will also address a number of other issues, Day said, including investment protection agreements to safeguard Canadian companies that invest in India.

"There are also all kinds of opportunities related to infrastructure," he said. "India's going through a huge growth period. They have recognized that Canada and Canadian businesses have much to offer in terms of expertise when it comes to infrastructure, when it comes to alternative energy sources, and we want to be there and ready to make those opportunities happen."

Harper has faced criticism from opposition MPs and business leaders for his government's strained relationship with China, Canada's third-largest export destination, since he took office in 2006.

The Tories angered Chinese officials in the early days of their minority government when they accused China of human rights abuses, and loudly protested the imprisonment of Chinese-Canadian Huseyin Celil.

NDP MP Thomas Mulcair said the Conservatives set the wrong tone in their relationship with China early on.

"(China is) becoming a world player and I don't think we have to start lecturing our partners," Mulcair told Question Period. "I'm wondering when was last time we heard the Conservatives lecturing the Americans on some of the shortcomings of their administration or their democracy?"

But Day said the Harper government is not interested in publicly hammering the Chinese over human rights issues.

"We take our relations with other countries in a very holistic way. When there are issues related to the values that are important to us as Canadians, we raise those, we deal with those," Day said.

"We want to see trade and opportunity also increase because with increased trade and increased movement across the border of goods and services, with that comes the transfer of ideas, comes the transfer of the very thought of how you raise the quality of life from one country to another."