Top officials from the EU and the South American bloc Mercosur signed a free trade agreement on Saturday in Paraguay, paving the way for the European Union’s largest-ever trade accord after 25 years of negotiations.

The agreement, designed to lower tariffs and boost trade between the two regions, must now gain the consent of the European Parliament and be ratified by the legislatures of Mercosur members Argentina, Brazil, Paraguay and Uruguay.

European Commission President Ursula von der Leyen and European Council President Antonio Costa joined the presidents of Mercosur countries at Saturday’s ceremony, with the exception of Brazilian President Luiz Inacio Lula da Silva, who sent his foreign minister.

The deal received the green light from most European nations last week, despite concerns from farmers and environmental groups, who fear a surge of inexpensive South American imports and increased deforestation.

Von der Leyen, who met with Lula before heading to Asuncion for the signing, said the deal would create the largest free trade zone in the world.