The four countries, which make up the pro-free trade Pacific Alliance group and have free-trade pacts with some of the world's largest economies, already have preferential tariffs aimed at boosting their exports.

Chilean President Sebastian Pinera said their goal was to scrap tariffs altogether for goods produced within the four nations, a position that stands in contrast to the more closed markets of South American trade bloc Mercosur.

"This means that at least 90 percent of the products are going to be freed from any kind of tariff in trade between our countries," Pinera told reporters during a summit of Latin American and European leaders in Chile that was dominated by trade issues.

"There will be a timetable to work on the remaining 10 percent until we reach 100 percent," he added.

Colombian President Juan Manuel Santos said the deal "represented perhaps the most significant and profound integration process in the history of Latin America."

Latin America is broadly divided between the Pacific countries that are free-trade advocates and the Mercosur states on the Atlantic side that have been more reluctant to drop barriers to trade.

Both Brazil and Argentina, which dominate Mercosur, have taken steps to boost local industry that critics call protectionist.

However, both countries agreed with the European Union during the two-day summit to revive stalled talks on a free-trade deal that would be a major prize for Europe as it emerges from crisis.

(Reporting by Moises Avila and Antonio De La Jara; Writing by Helen Popper; editing by Christopher Wilson)