In an emailed statement, NML criticized the tribunal for making a ruling.
"The Ghanaian courts have sole jurisdiction over this dispute, and that is where this matter has been and will continue to be lawfully heard," it said. "It is completely inappropriate for the International Tribunal for the Law of the Sea to attempt to interfere with orderly proceedings of the independent judiciary of Ghana."
Susana Ruiz Cerutti, the head of Argentina's delegation to the tribunal, was quoted by the Telam state news agency as praising the ruling for being unanimous and for siding with the vessel's captain, who had been accused of contempt.
It wasn't immediately clear how soon, or if, the ship would be allowed to set sail. The director-general of the Ghana Ports and Harbors Authority, Richard Anamoo, told The Associated Press that "it is not the port authorities that are holding the ship. We were only implementing a (Ghanaian) court order."
Argentina defense minister, Arturo Puricelli, said at a news conference in Buenos Aires that a charted plane would deliver 98 more sailors to Ghana on Wednesday to join the skeleton crew that stayed with the Libertad. He estimated the sailing ship could return to Buenos Aires by Jan. 9.
Associated Press writers Almudena Calatrava in Buenos Aires and Francis Kokutse in Accra, Ghana, contributed to this report.