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VINA DEL MAR, Chile, July 3 (Reuters) - There is no reason for Mexico's investment-grade credit ratings to be cut, the country's finance minister said on Friday amid worries over its economic health.

Agustin Carstens, who was speaking at a meeting of finance ministers from the Americas, rejected the view of some analysts who have said the country could be downgraded without key fiscal reforms.

"There is no solid reason to do revisions of Mexico's ratings," he said.

Carstens reiterated that the country's economy should shrink 5.5 percent this year as its trade flows with the United States slip.

"The truth is that nothing is defined. The main factor that could determine this adjustment, this revision, will be the fiscal policy measures that Mexico takes starting in September, when we present (to Congress) the budget and the economic program for Mexico for the coming year."

Fitch Ratings has said Mexico's weak macroeconomic outlook and rising fiscal pressures are weighing on its sovereign credit-worthiness.

H1N1 flu has hit the country, and the government needs to win backing in Congress for legislation that would try to reduce the country's reliance on oil revenues.

Mexico is one of few Latin American countries with investment-grade ratings.