U.S. Customs and Border Protection announced Wednesday that it has found much more cocaine aboard the MSC Gayane than originally thought – nearly 2.5 tonnes more, bringing the haul to about 18 tonnes in total. The $1.3 billion seizure is now officially the largest in the agency’s history.

A multi-agency team continues to remove and scan all containers from the 10,000 TEU MSC Gayane. Once the containers are removed, the team will conduct an examination of all compartments aboard the vessel in a search for any additional cocaine. The Gayane was due to depart last week, but as of Thursday, she remained moored in Phialdelphia.

“I can officially report that CBP has seized a historic amount of cocaine – in fact, the largest cocaine seizure in our 230-year history, with a weight of 39,525 pounds and a street value of about $1.3 billion dollars,” said Casey Durst, CBP’s Director of Field Operations in Baltimore. “This is a momentous accomplishment for the CBP team here in Philadelphia.”

Agents discovered the drugs when they spotted something unusual in seven shipping containers on the night of June 16. A CBP x-ray examination confirmed the find, and agents pulled about 15.5 tonnes of cocaine from the suspect boxes.

Six crewmembers from the MSC Gayane have been charged in connection with the seizure. According to Fonofaavae Tiasaga, a crewmember from the Gayane who has pleaded guilty to smuggling charges, the container ship’s crew brought the cocaine aboard in high-seas transfers involving 14 separate boats, which met up with the boxship while she was under way between Peru and Panama.

It was the second bust involving an MSC ship at the port since March, when authorities seized about 1,200 pounds of cocaine from containers aboard the MSC Desiree. CBP has suspended the line’s preferential customs inspection status, known as Customs Trade Partnership Against Terrorism (C-TPAT), in response to the two incidents. In a statement, MSC said that it is “committed to working with authorities and industry groups worldwide to improve the security of the international supply chain and ensure that illegal practices are dealt with promptly and thoroughly.”