Updated

A lumber dispute and the threat of bird flu were on the agenda for Secretary of State Condoleezza Rice's trip to Canada on Monday.

Rice's overnight trip to the Canadian capital of Ottawa was her first since taking over from Colin Powell (search) in January as the top U.S. diplomat. It had been delayed in part by U.S. resentment over Canada's refusal to join in a North American missile defense shield.

The trip also comes at a sensitive time in the bitter, years-old dispute over cheap Canadian lumber imports.

Canadian Prime Minister Paul Martin (search) said Monday he is willing to negotiate a softwood lumber agreement with the United States if Washington returns $3.5 billion in contested duties.

President Bush pressed Martin earlier this month for a negotiated settlement, but Martin rebuffed the overture and warned that Canada would sue in U.S. courts if necessary.

"Obviously, I think the Canadian relationship is working well," Martin said Monday. "We have differences and we are going to have those differences because I'm going to defend Canada. I'm not going to stop simply because, in fact, that the truth sometimes hurts."

The United States accuses Canada of sending millions of board feet of softwood lumber from government-owned timberlands across the border at low prices, making it tough for U.S. companies to compete.

The Bush administration imposed tariffs averaging 27 percent in 2002, which Canadian officials said was a reaction to lobbying pressure from the U.S. lumber industry.

"We'll raise it with Secretary Rice, asking her to understand our situation," Canadian Foreign Minister Pierre Pettigrew said in an interview with The Associated Press. "I do believe on this one the administration needs to stop taking assistance from the powerful lumber lobby."

North American Free Trade Agreement panels ruled in favor of Canada and said $3.5 billion in tariffs and duties collected on Canadian lumber were not justified. The United States has kept the tariffs in place and claims its position is supported by the World Trade Organization.

While Rice is in Ottawa, health ministers from 30 countries, infectious disease specialists and others are meeting in Toronto to look at a global emergency plan to ward off a bird flu pandemic. Canada is backing a Mexican proposal asking wealthy nations to set aside 10 percent of their stockpiles of antiviral medicines for developing nations.

Visits to neighbors Canada and Mexico are customary early in a secretary of state's tenure, and Rice visited Mexico in March.

A trip to Canada the same month was postponed. Although both nations said scheduling problems were chiefly to blame, the decision to postpone came amid U.S. frustration over the Canadian decision to opt out of a U.S.-backed plan to erect a North American anti-ballistic missile defense shield.

That dispute has not overshadowed U.S.-Canadian cooperation on other fronts, Pettigrew said.

"The relationship is much larger than that, and I have met with Secretary Rice often" in other settings, such as international conferences and at a U.S.-Mexico-Canada summit at Bush's Texas ranch, Pettigrew said.