By Stefanie Eschenbacher

MEXICO CITY (Reuters) -Mexico's top prosecutor said on Sunday that authorities have so far detained 14 people suspected to be involved in the illicit trade of fuels, reiterating that more actions would follow as new information comes to light.

On March 19, authorities seized a petroleum tanker in the Port of Tampico, together with nearly 63,000 barrels of diesel it was carrying, as well as containers and vehicles for its transport and storage.

The tanker, Challenge Procyon, had arrived from the United States, LSEG tanker-tracking data showed.

Mexican authorities said then that it was carrying diesel on which a special tax was due on import; instead, it had been declared to customs as a petrochemical exempt from the tax.

"This seizure is one of the largest in recent history related to this crime and started a series of investigative and intelligence efforts that revealed part of the criminal structure behind these activities," said the country's attorney general, Alejandro Gertz. "There'll be more actions."

Gertz added that these investigations had confirmed the existence of an organization dedicated to the theft and illegal trade of hydrocarbon products, which was using false documentation, complicit customs agencies and public officials.

Mexican authorities have not released company names and have given only the first names of the 14 people detained on suspicion of involvement in the crime, to protect their identity.

The investigations into these businessmen, active and retired naval officials and former customs officials, are ongoing.

Raymundo Morales, head of the Mexican Navy, said at the same press conference in Mexico City that the Navy had strengthened internal controls and disciplinary procedures to prevent and eradicate the illegal import of fuels.

"We're protecting the institution without excusing isolated individual behaviors that violate public trust," he added, speaking alongside Gertz and the security minister, Omar Garcia Harfuch.

(Reporting by Stefanie Eschenbacher in Mexico City; Editing by Matthew Lewis)