Federal prosecutors in Philadelphia have seized a container ship operated by the Mediterranean Shipping Co. and owned by JPMorgan Asset Management.

That came weeks after authorities found more than $1 billion worth of cocaine on the vessel in what was one of the largest drug busts in American history.

At least a half a dozen crew members have been arrested, according to Homeland Security Investigations, and the investigation is ongoing.

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Federal prosecutors in Philadelphia have seized a container ship operated by the Mediterranean Shipping Co., weeks after authorities found more than $1 billion worth of cocaine on the vessel in what was one of the largest drug busts in American history.

US Customs and Border Protection seized the ship on July 4, a statement out Monday said. The ship is owned by client assets in a maritime strategy offered by JPMorgan Asset Management, according to a person familiar with the matter. It is operated by the Switzerland-based MSC.

On June 18, CBP agents found 39,525 pounds of cocaine stashed in several containers on the MSC Gayane at the Philadelphia seaport. The street value of the drugs was estimated at about $1.3 billion, making it the largest cocaine seizure by the agency.

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"A seizure of a vessel this massive is complicated and unprecedented - but it is appropriate because the circumstances here are also unprecedented," said US Attorney William McSwain. "We found nearly 20 tons of cocaine hidden on this ship."

At least a half a dozen crew members have been arrested, according to Homeland Security Investigations, and the investigation is ongoing. Charges included conspiracy to possess cocaine aboard a ship.

The Gayane sailed under the flag of Liberia and had previously traveled through the Bahamas and several South American countries, according to an online ship tracker.

JPMorgan declined to comment. Mediterranean Shipping Co. did not immediately respond to an email inquiry.

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