Canada, long one of Cuba's top trade and political partners, is cooling its relations with Havana in response to a crackdown on dissent earlier this year, the Ottawa government confirmed Tuesday.

Canada has already canceled two aid projects for Cuba and two proposed visits by Cabinet ministers, and will review all future programs and visits on a case-by-case basis, government officials said.

Canada also recently halted its unsuccessful campaign to restore Cuba's membership in the Organization of American States, suspended since the early 1960s, government spokesmen confirmed.

While the sanctions appeared relatively minor, the moves may add to Cuba's increasingly negative public image in Canada, a nation that has long stood as one of Havana's top friends in the Americas, along with Mexico.

The announcements came amid Canadian and U.S. media reports detailing complaints by some Canadian investors that the Cuban government has cheated them out of millions of dollars.

Canada is Cuba's third-largest trade partner, behind Russia and Spain, and its citizens form the single largest group of vacationers who fuel the island's $1.8 billion tourism industry.

But Ottawa's policy of maintaining warm relations with Cuba in hopes of slowly pushing the Communist government to embrace reforms suffered a setback in March when Havana convicted four opposition leaders on charges of sedition and put a harsh new law on dissent into effect.

Canadian Prime Minister Jean Chretien was said to have been particularly irritated by the four dissidents' convictions because he had asked President Fidel Castro for their freedom during a meeting in Havana last year.

``We believe our `constructive engagement' approach remains the most appropriate tool for advancing our interest in Cuba, but we decided to redefine the framework,'' said Christian Girouard, spokesman for the Department of Foreign Affairs and International Trade.

``We will now review all projects, on a case-by-case basis, to make sure the projects we do support do in fact help to improve the human rights situation and promote economic reforms.''

He confirmed a report on the policy shifts in Tuesday's Globe and Mail newspaper, but said the decision to change the basis of relations with Cuba had in fact been made in mid-April.