World leaders at a U.N. summit pledged Thursday to reduce trade barriers and boost agricultural production to combat a food crisis that is spreading hunger and violent unrest across the world.

After three days of wrangling, delegates from about 180 countries approved a declaration resolving to ease suffering caused by soaring food prices and step up investment in agriculture.

A few Latin American countries raised strong objections to the declaration. Cuba was disappointed the document didn't blast the long-standing U.S. embargo against the Communist-run island, and Argentina said it was unhappy over the trade-barrier language.

The declaration urged help for farmers in poor countries who need seed and fertilizers in time for approaching planting season.