Nicaragua's government is criticizing Costa Rica for bringing outside experts to visit a disputed border area.
Costa Rica has been protesting Nicaragua's dragging of the San Juan border river and also alleges incursions by Nicaraguan troops.
Costa Rica invited wetlands experts to view environmental damage it says has been caused by the dragging. A Costa Rican government legal adviser says a group of protesters showed up from the Nicaraguan side and interfered with the visit Tuesday.
Nicaragua's presidential office contends the visit violates a March cooling-off order from the International Court of Justice. The court told both countries to keep their military, police and civilian personnel out of the disputed area.