It was due to offload in Algeria's western port of Oran but suspicions were raised when the captain refused to dock for three days.
Acting on a tip-off, the Algerian coastguard forced the boat into port. The drugs were then found aboard the Liberian-registered ship, the Vega Mercury, in boxes marked "halal meat".
Algerian authorities have seized more than 700kg (1,543lb) of cocaine smuggled aboard a container ship and made 20 arrests.
The vessel was carrying frozen meat from Brazil and had previously docked in Valencia, Spain.
