Mexican authorities have found a consignment of cocaine hidden in coal brought in on a bulker.
Secretariat of the Navy said on Twitter that it carried out a joint operation with customs officials involving the 37,000-dwt ES Jupiter (built 2014) at the port of Lazaro Cardenas.
Video footage shows a digger raking through coal on the quayside.
The ship arrived on 7 July after earlier calling at Buenaventura, Colombia.
Three bags containing 140 packets of cocaine were found. They weighed 162 kg.
Probe continuing
Manager Glory Ships said: "The vessel was loaded with a cargo of metallurgical coke in bulk at Buenaventura, Colombia, for carriage to Lazaro Cardenas in Mexico.
"Prior to and during loading of the cargo, extraordinary security measures were deployed beyond those typically prescribed, and following final checks by the local authorities all was confirmed to be in order."
It added that two packages were then located in the cargo holds with unknown contents at the Mexican port.
"It is suspected that they contain illegal substances, but this has not yet been officially confirmed," it said.
"The competent authorities were promptly informed and enjoy the full co-operation of the managers and the owners of the vessel, who always comply fully with all international, regional and national laws and regulations."
Glory Ships said the investigation was ongoing and it was hopeful the vessel would depart soon "as this incident has nothing to do with the owners or the vessel/her crew."
Drug seizures on bulkers are less common than on containerships, where drugs are often stashed in boxes.
New methods
Most smuggling reported on dry cargo ships involves devices attached to hulls, or contraband stashed in places like chain lockers or fuel tanks.
But traffickers are nothing if not creative, with new techniques being tried out on a regular basis.
Earlier this month in Mexico, two smugglers disguised as dock workers were found in a container with cocaine on board the 9,640-teu Maersk Svendborg (built 1998) in Manzanillo.
The most recent report bulker smuggling case took place in Germany, when police seized 500 kg of cocaine on board a Barska Plovidba vessel in Hamburg in May.
The 35,000-dwt Budva (built 2014) had arrived from Brazil via Morocco when it was raided as part of a joint action between the US Drug Enforcement Agency and police from the UK, Portugal, Spain, Germany and the Netherlands.
The cocaine was found hidden in what was described as a cargo area on the ship.
Last year, a Golden Ocean capesize bulker was stopped in South Korea after the discovery of a large quantity of cocaine aboard.
The Korea Coast Guard said police found 101 kg of the drug worth roughly $250m hidden in plastic bags.
The John Fredriksen company and Wallem Shipmanagement confirmed the ship was the 181,000-dwt Golden Savannah (built 2017).
