U.S., 4 Central American countries reach agreement on trade pact.(Knight Ridder Newspapers)

Byline: Jane Bussey

MIAMI _ The United States and four Central American countries reached agreement Wednesday on a free trade pact that broadens and deepens existing trade ties with a region still mired in poverty and slow growth.

But the trade pact lost some of its luster when Costa Rica, the most prosperous of the developing Central American nations, withdrew from the talks just hours before negotiators completed their last round-the-clock session that ended early Wednesday.

In a news conference with the Central American trade ministers, U.S. Trade Representative Robert B. Zoellick called the agreement "a cutting edge, modern free trade agreement designed to tear down the tariff walls that block trade between the United States and Central …