DAKAR, Senegal  Thousands of victims of one of the worst toxic dumping scandals in years could lose their hard-won settlement thanks to maneuverings by a shadowy but “influential” figure in Ivory Coast, where the dumping occurred, the victims’ lawyer said Wednesday.

Up to $45 million in compensation is at stake, intended for about 30,000 victims of an oil-based sludge surreptitiously dumped around Abidjan, Ivory Coast’s capital, in 2006. The tanker’s poisonous shipment has become notorious as a kind of African Bhopal, an example of a multinational corporation’s negligence in the third world.

The waste was shipped by Trafigura, an international commodities trading giant. About 108,000 people sought treatment for nausea, headaches, vomiting and abdominal pains, and at least 15 died. All had apparently been poisoned by the toxic brew of gasoline and caustic soda, refining byproducts dumped by Trafigura’s contractor.

The company agreed to pay the Ivorian government about $200 million in 2007, then settled separately with the victims in September of this year. But now the money, frozen in a local bank, has been claimed by a largely self-appointed community representative named Claude Gohourou. In recent weeks, the Ivorian judiciary has sided with him, according to the London law firm Leigh Day & Company, which represents the victims.