Family of environmental activist Ken Saro-Wiwa, hanged by his country's rulers in 1995, take oil giant to court in New York

Ken Saro-Wiwa swore that one day Shell, the oil giant, would answer for his death in a court of law. Next month, 14 years after his execution, the Nigerian environmental activist's dying wish is to be fulfilled.

In a New York federal court, Shell and one of its senior executives are to face charges that in the early 1990s in Nigeria they were complicit in human rights abuses, including summary execution and torture.

The Anglo-Dutch company, if found liable, could be forced to pay hundreds of millions of pounds in damages. No multinational has ever been found guilty of human rights abuses, although two previous cases saw major claims settled outside court.

Saro-Wiwa became famous as a campaigner on behalf of the Ogoni people, leading peaceful protests against the environmental damage caused by oil companies in the Niger Delta. There was worldwide condemnation when, along with eight other activists, he was hanged by the Nigerian military government in 1995 after being charged with incitement to murder after the death of four Ogoni elders. Many of the prosecution witnesses later admitted that they had been bribed to give evidence against Saro-Wiwa, who was a respected television writer and businessman.

Lawyers in New York will allege that Shell actively subsidised a campaign of terror by security forces in the Niger Delta and attempted to influence the trial that led to Saro-Wiwa's execution. The lawsuit alleges that the company attempted to bribe two witnesses in his trial to testify against him. Members of Saro-Wiwa's family will take the stand for the first time to give their version of events, among them his brother Owens, who will allege that Brian Anderson, managing director of Shell's Nigerian subsidiary, told him: "It would not be impossible to get charges dropped if protests were called off." Anderson is fighting the action.

Witnesses who were shot by military police in the Niger Delta principally to protect the building of Shell's oil pipeline will allege that Shell, by paying the police to protect its interests, was complicit in acts of violence.

Speaking to the Observer from Abuja, Nigeria, Saro-Wiwa's son, Ken Wiwa, said: "For 14 years we have lived with the memory of a father, an uncle, a brother, a son executed for a crime he didn't commit. We have daily reminders. It's painful to live with a monstrous injustice. To wake up one day to finally get our day in court is tremendously satisfying.

"After the injustice of the original crime against my father, having to watch legal arguments [by Shell] using the highest-paid lawyers in the world is sickening. You can't describe how painful that is to go through.

"Part of the reason for the original protest was the way Shell behaved. Ogoni people made their living farming and fishing, but Shell was using open waste pits and oil pipelines criss-crossed the land. These polluting activities were put on top of a delicate ecosystem. It destroyed people's ability to sustain themselves. That's the impact of Shell and, when people tried to protest, they were brutally repressed."

In a statement, Shell this weekend described the executions of the Ogoni 9 as "tragic events carried out by the Nigerian government in power at the time".

"Shell attempted to persuade that government to grant clemency; to our deep regret, that appeal - and the appeals of many others - went unheard, and we were shocked and saddened when we heard the news. Shell in no way encouraged or advocated any act of violence against them or their fellow Ogonis. We believe that the evidence will show clearly that Shell was not responsible for these tragic events. The allegations made in the complaints against Royal Dutch/Shell concerning the 1995 executions of Ken Saro-Wiwa and his eight fellow Ogonis are false and without merit."

US lawyers have finally won permission to bring the case to court under the alien tort statute, which gives non-US citizens the right to file claims in American courts for international human rights violations. The court case had been set for 27 April, though last night the date was moved to 26 May.

Today the oil-producing Niger Delta region is riven by intense violence and corruption. The Ogoni 9 trial is seen as a way of coming to terms with the past and building a non-violent future.

"We need to know the truth," said Ken Wiwa last night. "We need to have people account for their role in the executions and the displacement of the Ogoni people, many of whom feel traumatised. It will be a relief. It will enable people to face the future. That's the most important thing. Let's account for the past, so we can move forward."

Lawyers representing Saro-Wiwa's family have not sought specific damages should Shell be found liable, but legal experts say the oil giant could face fines running into hundreds of millions of pounds.

Jenny Green, a senior lawyer at the New York-based Center for Constitutional Rights, who has played a pivotal role in ensuring the Saro-Wiwa case made it to court, said: "Mosop [the Movement for the Survival of the Ogoni People] was formed to stand up to multinationals and the dictatorship that acted hand-in-hand. This is a significant moment, because it says you can't act with impunity."