THE HAGUE, Netherlands (AP) — The widows of four Nigerian activists have opened a civil court case against oil company Shell, alleging it was complicit in the deaths of their husbands more than two decades ago.

Esther Kiobel, Victoria Bera, Blessing Eawo and Charity Levula are seeking an apology and compensation in the case that opened Tuesday in The Hague, in the Netherlands.

Their husbands were among nine activists from the Ogoni tribe, led by writer Ken Saro-Wiwa, who were hanged in 1995 for the murder of four political rivals. Supporters say they were targeted because of their involvement in protests against environmental damage by Shell's Nigerian subsidiary.

In a written statement, Shell's Nigerian arm, Shell Petroleum Development Company of Nigeria Limited, denied responsibility. The company says it did "had no role in the arrest, trial and execution of these men."