The presidents of Argentina, Brazil, Paraguay and Uruguay will appear together in the city of Santa Fe, in Argentina's Pampas grains belt, less than a month after agreeing the landmark deal.
The deal, 20 years in the making, marks a rare win for free trade amid increasing global protectionism, though it still needs to be ratified, in principle, by the different national parliaments involved. Mercosur leaders, however, indicated they were keen to find a way to speed up implementation of the deal.
"We are all in favour that the deal could have a provisional entry point, because of the discussions each member (of Mercosur) is having with their own parliaments," Argentine foreign minister Jorge Faurie told reporters late on Tuesday.
Horacio Reyser, the country's secretary of international economic relations, added the deal should be able to come into effect provisionally with the agreement of the European Parliament, even before each member state signed off.
The deal between two of the world's largest trade blocs has been cheered by leaders in both regions, though it has raised some concerns about rising competition among farmers in Europe and industrial sectors such as automobiles in South America.
The Mercosur trade bloc also now has its eye on further trade deals, including longer-term discussions for an agreement with the United States.
The bloc is also in negotiations with the EFTA bloc - made up of Iceland, Norway, Liechtenstein and Switzerland - and with Canada to reach treaties similar to the one agreed with the EU.
Faurie said a deal with EFTA could be stuck in the second half of the year and with Canada in the first half of 2020.
The presidents of Bolivia and Chile, not formal Mercosur members but with close ties in the region, will also participate in the summit of leaders in Santa Fe, where there was a strong police presence in the streets on Wednesday.
The meeting will see Brazil take over the presidency of the Mercosur trade bloc from Argentina.
(Reporting by Maximilian Heath; Writing by Adam Jourdan; Editing by Susan Thomas)
By Maximilian Heath
