Leaders of Mexico and seven Central American countries have agreed to move ahead with a $3.5 billion plan to upgrade highways from southern Mexico to Panama.

The highway agreement was one of several accords reached at the two-day summit on the Yucatan peninsula.

The leaders met to advance their year-old Puebla-Panama Plan, the brainchild of Mexican President Vicente Fox. President Fox is promoting development in the impoverished region as a way to stem the flow of migrants to the United States.

The plan aims to link southern Mexico with Central America, improving highways and standardizing customs procedures to stimulate trade. It also seeks to join power grids to lower electricity rates.

Leaders of Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Belize and Panama attended the Merida, Mexico, summit. They wrapped up the summit Friday by endorsing a statement condemning terrorism and promising to do more to uphold human rights in the region.