The widows of four of nine men executed by Nigeria’s military regime in 1995 have filed a civil lawsuit seeking compensation and an apology from Royal Dutch Shell.

The widows are Esther Kiobel, Victoria Bera, Blessing Eawo and Charity Levula.

According to a writ filed in a court in The Hague, the widows are seeking compensation from the company for alleged complicity in a military crackdown, leading to the deaths of their husbands.

The Nigerian military cracked down heavily on local opposition to oil production by a Shell joint venture in the Niger Delta region in the early 1990s.

The suit filed by the four widows alleged that Shell provided support to the military in the crackdown that ultimately led to the executions of the men, known as the Ogoni 9.

But Shell, the largest oil producer in Nigeria, has repeatedly denied any involvement in the executions or the government’s response to the unrest.

A statement by the multinational said the company did not collude with the military, adding that it believed in dialogue.

“We have always denied, in the strongest possible terms, the allegations made by the plaintiffs in this tragic case,” the statement said Wednesday.

“SPDC (Shell Petroleum Development Company of Nigeria) did not collude with the authorities to suppress community unrest and in no way encouraged or advocated any act of violence in Nigeria. In fact, the company believes that dialogue is the best way to resolve disputes.”

In 2009, Shell agreed in an out-of-court settlement in the United States to pay $15.5 million in damages to a group of relatives of the nine.

The four widows’ civil case, according to Reuters News agency report, was filed by human rights lawfirm Prakken d’Oliveira with the support of Amnesty International.

“Shell and the military regime formed an alliance in the events leading to the deaths of the Ogoni 9,” the writ said.

“Their relationship was one of mutual dependence: the Nigerian state was dependent on the income from oil that Shell generated; in turn, Shell was dependent on the benevolence and protection of the regime to pursue its activities in Nigeria and in this way realise a substantial part of its turnover.”

The writ however did not specify how much compensation they were seeking.

Earlier, Kiobel had taken a lawsuit to the United States, but the U.S. Supreme Court ruled in 2013 that the case could not be heard because the country did not have jurisdiction.

A number of groups have pursued in recent years cases against Shell in courts in the United Kingdom, the United States and the Netherlands over claims related to oil spills and environmental damage, claiming they cannot get a fair hearing in Nigeria.

The Ogoni Nine were a group of nine activists from the Ogoni region of Nigeria. They were led by outspoken author and playwright Ken Saro-Wiwa, who had previously been a critic of the Royal Dutch Shell oil corporation, and had been imprisoned for a year prior to the executions in November 1995.

Others are Saturday Dobee, Nordu Eawo, Daniel Gbooko, Paul Levera, Felix Nuate, Baribor Bera, Barinem Kiobel, and John Kpuine.

They were executed by hanging in 1995 by the military dictatorship of Sani Abacha and buried in Port Harcourt Cemetery.

The executions provoked international condemnation and led to the increasing treatment of Nigeria as a pariah state until Mr. Abacha’s death in 1998.