New Delhi, Feb. 28 -- Uruguay and Argentina on Thursday became the first founding members of the Mercosur bloc of South American nations to ratify a long-sought free-trade agreement with the European Union to establish one of the world's largest free-trade zones.

The deal has been negotiated for a quarter century among countries that are now home to more than 700 million people and account for a quarter of global gross domestic product. It passed Uruguay's lower house with a landslide 91-2 vote, mirroring the Senate's unanimous support the previous day.

"Uruguay has sent a strong message to the United States, Mercosur and Europe: that we have waited 25 years, but we are not willing to wait a single second longer," Congressman Juan Marti...