Canada must sign up to a proposed 12-nation Pacific trade pact, even though the country's auto makers might not be happy with some of the conditions, Prime Minister Stephen Harper said on Thursday.

Trade ministers failed to clinch the Trans-Pacific Partnership at a meeting in late July amid disagreements over sectors such as autos and dairy.

U.S. President Barack Obama said on Wednesday he was confident a deal could be finalised this year.

Canada and Mexico, both home to major auto plants, are angry that the United States wants to let Japan export cars to North America with substantial content from non-TPP nations. This, they fear, could make Canadian and Mexican autos too expensive.

Harper - predicting the talks would succeed in producing a trade deal - told a televised election campaign debate that Canada had no choice but to join the TPP to ensure access to fast-growing Asian markets.