Argentina has called on the United Nations' highest court to order that Uruguay halt construction of two pulp mills along their joint border.
The argument was made Thursday before the International Court of Justice in The Hague. The court is holding two days of hearings on the issue.
A representative for Argentina alleged that the mills, which are being constructed along the Uruguay River, would emit dangerous toxins that would damage the fragile river ecosystem and threaten the health of residents.
But a professor representing Uruguay dismissed the claim, saying Argentina had not presented any evidence to substantiate its argument.
He said Uruguay's first priority with the pulp mills is to protect the environment and the health of the residents on both sides of the river.
The Argentine government also accuses Uruguay of violating a 1975 treaty that calls for the nations to notify and consult the other about any action related to the river.
Some information for this report was provided by AP and Reuters.