Prime Minister Stephen Harper is leading a trade delegation to South Korea, one expected to wrap up a free trade pact with the country.

Mr. Harper, International Trade Minister Ed Fast and Industry Minister James Moore left Ottawa for Seoul on Sunday morning. The delegation is scheduled to meet with South Korean president Park Geun-hye to "discuss ways to increase trade and investment," the Prime Minister's Office said.

Canada and South Korea have been in the final stages of trade talks, which Mr. Harper has previously said he expected could be complete this year.

Mr. Harper's presence on the trip signals a deal has been reached, though Mr. Fast said Sunday they were putting the "finishing touches" on the pact.

"I'm not going to prejudge the outcome of his visit, but we're going there with optimism that we'll be able to conclude negotiations," he told CTV's Question Period in an interview aired Sunday morning.

The opposition parties warn, however, the deal will be impossible to assess without knowing details of concessions Canada made in negotiations.

A trade deal with South Korea would be Canada's first with a major Asian nation, and is seen as something of a beachhead for other negotiations aimed at boosting trade with the region.

The auto sector has been a vocal opponent of the deal, saying the pact could give an advantage to Korean car makers, such as Hyundai and Kia. The 6.1 per cent duty Canada levies on Korean cars has been a stumbling block in talks.

Mr. Fast said the looming deal will address "some" of the concern of the auto sector, a key industry in southern Ontario, but that its "narrow interests" are being overshadowed.

"We have broad consultations with the auto industry, and we believe the outcome we're hoping to achieve will be a balanced one. It will reflect many of the concerns raised by the auto industry. But understand - my role isn't simply to promote the narrow interest of the auto sector itself. My role is to promote the national interest. Virtually every other sector of our economy has told us this trade agreement is absolutely critical," Mr. Fast told CTV.

Don Davies, the international trade critic for the Official Opposition NDP, warned the deal will be impossible to assess without knowing details, which have not been released. Details of the Canada-EU trade deal, announced that fall, also haven't been released, he said.

"We support a good trade agreement with South Korea and we support increased trade relations with Asia... on the downside, we have no details and trade deals are all about details," Mr. Davies said Sunday. "...Just signing a deal isn't enough."

Liberal International Trade Critic Chrystia Freeland expressed a similar sense of cautious optimism.

"Our party and our position is very much supportive of trade and openness to trade. Canada is a small country in a big world economy. And we believe that trade is an essential part of economic growth and a better deal for the Canadian middle class. Having said that, the devil's in the details and we don't know them yet. So we'll wait and see," she said.

After South Korea struck trade deals with the United States and European Union, Canada's agriculture exports to South Korea have plummeted, he said. If Mr. Harper signs a deal, it then needs to be translated and finalized, a process Mr. Fast hopes could take as little as one year. "This is absolutely critical for Canada's economic welfare," he told CTV.

However, Ford president Dianne Craig cited earlier deals in arguing against a Canadian pact, saying the South Korea-U.S. deal failed to remove South Korean trade barriers. "This is not good for autos, which means it's not good for the economy, which means it's not good for Canadians," Ms. Craig said in January.

Chrysler Group LLC opposed the deal, but backed down after a meeting last month between Mr. Harper and Chrysler chief executive officer Sergio Marchionne. General Motors of Canada Ltd. has not taken a position publicly.

Asked about the impact on the auto sector, Mr. Davies said the Koreans should drop tariffs and invest in producing cars within Canada in order for Canada to lower its tariffs.

"Tariffs should be eliminated if there's meaningful investment here and there's reciprocity," Mr. Davies said, saying barriers for trade with South Korea remain in place for American exporters, despite a deal.

"We have to make sure Korea is giving us real and meaningful access to Korean markets. There's a real significant game being played by countries in terms of non-tariff barriers," he said.

Ford of Canada had no immediate comment Sunday afternoon. A spokesman for the Canadian Manufacturers and Exporters industry group said it would wait to see terms of the deal before commenting on it.

The negotiations have gone on for years, but a key turning point was said to have come in October at the Asia-Pacific Economic Co-operation summit Indonesia, where Mr. Harper and Ms. Park agreed to fast-track the talks.

South Korea is Canada's seventh-largest "merchandise trading partner," and its third-largest in Asia, trailing China and Japan, according to the Prime Minister's Office. The South Korea visit is Mr. Harper's fourth as Prime Minister.