Canada and the United States are finding themselves at odds with Latin American countries on two thorny issues — the war on drugs and the exclusion of Cuba — at a summit of hemispheric leaders in Colombia.

The event's host, Colombian President Juan Manuel Santos, delivered a frank speech Saturday to the assembled heads of state and government in which he said it would be "unacceptable" to hold another Summit of the Americas without Cuba. The communist country was suspended from the Organization of American States, the main organizing body for the summits, in 1962.

Canada and the United States are the only two countries in the organization that have not lobbied to invite to Cuba to the events.

"The isolation, the embargo, the indifference, the looking the other way don't work," Santos said in the coastal resort city of Cartagena. "It's an anachronism that keeps us anchored in a Cold War era that was overcome decades ago."

Three Latin American leaders are threatening not to sign Sunday's summit declaration unless Canada and the United States agree to allow Cuba to attend the next one, the CBC's Terry Milewski reported from the summit.

Divided over drugs

The Colombian president also said that the war on drugs isn't working and that he would like to see a debate on decriminalizing them.

Violence related to the drug trade has pushed murder rates in Central America and the Caribbean to the highest in the world.

But Canadian Prime Minister Stephen Harper's office has said he won't entertain any policy changes that would lift the prohibition of illicit drugs, while U.S. President Barack Obama repeated at the summit on Saturday that the White House believes "legalization is not the answer."

Saturday's focus on Cuba and drug enforcement policy clashed with Harper's agenda at the summit, which was to sell Canada as an attractive destination to do business.

The prime minister went looking for investment dollars from across the region during a speech Saturday to assembled leaders, where he boasted of Canada's economic stability and strong resource industry.

Harper also told a forum of CEOs his government's budget promises to speed up the regulatory process to develop major natural resource projects is a key reason they should invest.

"We cannot allow valid concerns about environmental protection to be used as an excuse to trap worthwhile projects in reviews without end," Harper said. "What matters is that the relevant facts are fully considered. That need not take years."

Harper further touted Canada’s banks as "the soundest in the world" according to the World Economic Forum.

Canadian exports have been flagging over the past several years, and Canadian manufacturing has felt the blow with an estimated 500,000 lost jobs. At the same time, South American countries have seen strong economic growth and are an appealing destination for potential trade and investment.

Latin American leaders have been working to take advantage, having recently founded the Community of Latin American and Caribbean States, which includes all of the hemisphere's countries except Canada and the United States.

With files from The Canadian Press