The International Court of Justice on Thursday said it would consider a claim by Nicaragua to expand its maritime boundaries in a mineral-rich part of the Caribbean Sea toward Colombia, a ruling set to further strain relations between the two countries.
The judgment, separate from a decision earlier on Thursday in which the United Nations court said it would rule on alleged violations of Nicaragua's sovereignty, means a maritime delineation case between the two countries can proceed.
In a televised address soon after the decision, Colombian President Juan Manuel Santos said he would not accept a ruling by a "third party" and would not participate in the case.
"Bilateral issues between Nicaragua and Colombia will not be subject to decisions made by third parties and should be handled via direct negotiations in conformity with international law," he said.
Diplomatic relations between the two nations have suffered over the dispute, which intensified after a 2012 ruling by the court that drew a demarcation line in favor of Nicaragua in Caribbean waters, reducing the expanse of sea belonging to Colombia.
The decision increased the size of Nicaragua's continental shelf and economic exclusion zone in the Caribbean, potentially giving it access to underwater oil and gas deposits as well as fishing rights.
Colombia has not accepted that ruling, prompting Nicaragua to seek a judgment from the court to force it to abide by the decision.
In the new case, judges are being asked to settle boundaries beyond the 200 nautical miles that were fixed by the 2012 judgment.
Nicaragua said it was satisfied by the ruling.
"This is a total victory for Nicaragua," said Carlos Arguello, Nicaragua's representative at the Hague. "This sends a clear message that the court's rulings need to be respected."
Reporting by Helen Murphy, Thomas Escritt and Ivan Castro