Royal Dutch Shell, the big oil company, agreed to pay $15.5 million to settle a case accusing it of taking part in human rights abuses in the Niger Delta in the early 1990s, a striking sum given that the company has denied any wrongdoing.

The settlement, announced late Monday, came days before the start of a trial in New York that was expected to reveal extensive details of Shell’s activities in the Niger Delta.

The announcement caps a protracted legal battle that began shortly after the death of the Nigerian activist Ken Saro-Wiwa in 1995. Mr. Saro-Wiwa, Shell’s most prominent critic at the time in Nigeria, was hanged by that country’s military regime after protesting the company’s environmental practices in the oil-rich delta, especially in his native Ogoni region.

Shell continued Monday to deny any role in the death. It called the settlement a “humanitarian gesture” meant to compensate the plaintiffs, including Mr. Saro-Wiwa’s family, for their loss and to cover a portion of their legal fees and costs. Some of the money will go into an educational and social trust fund intended to benefit the Ogoni people.