Brazil, Paraguay, Bolivia and Uruguay have urged Argentina to stop applying tolls for ships and barges carrying grains and other exports, saying it restricts navigation on a key river channel.
The four countries issued a joint statement late on Sunday blasting as "unilateral and arbitrary" Argentina's decision to seize a barge from Mercurio Group, a Paraguayan shipping company, to collect a toll, adding its actions could affect supply and prices.
The barge was released on Monday after paying the toll, a company spokesperson told local radio.
Argentine authorities say tolls on the Paraguay-Parana waterway, a key transport route to the sea for inland areas of Paraguay, Bolivia and south Brazil, are needed to maintain the 3,400 kilometer (2,110 mile) channel that ends at Buenos Aires.
Argentina's energy minister is set to meet with Paraguay's foreign minister later on Monday to address the matter.
Argentina, which saw its recent soy and corn harvests battered by drought, has imported over 7 million metric tons of soybeans in the first seven months of this year, 51% from Paraguay and 45% from Brazil, according to official data.
Paraguay recently announced it will go to the Mercosur trade bloc Permanent Review Court to resolve the dispute.
(Reuters - Reporting by Daniela Desantis; Additional reporting by Maximilian Heath and Lucila Sigal; Writing by Valentine Hilaire; editing by Timothy Gardner)