Four more seafarers have been charged following the seizure of cocaine worth more than $1bn on an MSC boxship in Philadelphia.

Crewmen Ivan Durasevic and Fonofaavae Tiasaga were charged with smuggling by US authorities earlier in the week.

MSC Gayane's route to Philadelphia Photo: VesselsValue

The Philadelphia Inquirer cited sources as saying the latest quartet to be charged are Bosco Markovic, 37; Alekandar Kavaja, 25; Nenad Ilic, 39; and Laauli Pulu, 32.

They remain in custody after making their first court appearance on Wednesday afternoon, it reported.

The amount of drugs was initially put at 15.5 tons, but has been revised up to 17.5 tons, CBS said.

VesselsValue assesses the ship as worth $84m, 7.6% of the estimated $1.1bn value of the drugs.