The UN's top court will give its verdict Thursday in the latest legal battle between Colombia and Nicaragua over an oil and fish-rich swathe of the Caribbean Sea.
The Latin American rivals have been fighting it out for more than two decades at the International Court of Justice (ICJ) over their maritime boundaries.
Judges will hand down the ruling at the court's headquarters in The Hague at 3:00 pm (1300 GMT).
Nicaragua, in Central America, is disputing a 2012 ruling by the Hague-based ICJ that gave it a large chunk of the Caribbean, while awarding seven small islands to Colombia, in South America.
The following year Nicaragua went back to court to argue that its territory should extend beyond the 200 nautical miles (230 miles, 370 kilometres) from its coastline that is customary under international law.
Managua argues that its territory should instead follow the continental shelf that extends under the sea from its coastline.
But Colombia disputes this, saying it overlaps with the area in which the archipelago of islands is located.
The ICJ in a related case ordered the Colombian navy in 2022 to stop interfering in Nicaraguan waters.
"In this dispute, maritime areas rich in biodiversity, fishing resources, scenic beauty, but also natural resources such as hydrocarbons are at stake," Nicolas Boeglin, professor of public international law at the University of Costa Rica, told AFP.
- 'Exorbitant' demands -
The two sides exchanged barbs in court during hearings in December last year, with Colombia accusing Nicaragua of making the most "exorbitant" demands in legal history.
It said Nicaragua "did not scientifically demonstrate that it has a continental shelf" that extends beyond 200 miles.
Nicaragua meanwhile accused Colombia of threatening the "public order of the ocean".
Nicaragua and Colombia share no land borders but diplomatic relations have been strained for almost a century over disputed maritime limits.
Nicaragua finally took Colombia to the court in 2001, and in 2012 it won several thousand square kilometres of territory in the Caribbean that had previously been Colombian.
A furious Colombia, which was left with only seven islets, said at the time it would no longer recognise the court's jurisdiction on border disputes.
Nicaragua then went back to the court in 2013 alleging that Colombia had carried out violations of the judgment.
The International Court of Justice was set up after World War II to rule in disputes between UN member states. Its judgments are final and cannot be appealed.
A number of Latin American states including Chile and Bolivia, Guyana and Venezuela, and Guatemala and Belize have asked the ICJ in recent years to resolve decades, or in some cases centuries-old territorial claims.
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