AMSTERDAM  - The city of Amsterdam must face full responsibility for failing to supervise a ship that later dumped toxic waste in the economic capital of the Ivory Coast, the Dutch supreme court ruled on Wednesday.

In 2006, slops from the cargo ship Probo Koala, chartered by commodities trader Trafigura, were dumped in the West African city of Abidjan, the main city in Ivory Coast.

Trafigura hired a contractor in 2006 to dispose of slops from the Probo Koala. It described the petrochemical waste as residues from gasoline, mixed with caustic washings.

The high court overturned an appeals court ruling that had absolved Amsterdam of responsibility for allowing toxic waste onto the ship.

At the same time, the Dutch high court left intact an appeals court ruling that said the city could be held responsible for its supervisory role in monitoring the ship.

Last September Trafigura said it reached a settlement with thousands of people who claimed they had fallen ill from the dumped waste.

Trafigura, one of the world's biggest commodities traders with offices in Geneva, Amsterdam and London, repeatedly has denied any wrongdoing in relation to the 2006 incident.

The company agreed to a $198 million out-of-court settlement with the Ivory Coast government in 2007, which exempts it from legal proceedings in there.