A Dutch court has ruled that it has jurisdiction to determine whether Royal Dutch Shell was complicit in the Nigerian government’s execution of the Ogoni Nine, environmental protesters who fought against widespread pollution in the Niger Delta.

In a 50-page ruling hailed by campaigners as an “important precedent” for global human rights cases, judges at The Hague’s district court said on Wednesday that they would allow the case to go forward, also indicating that the claimants – widows of four of the activists – would be able to bring further evidence to prove their case.

The ruling, which was partially read out to members of the public, also stipulated that the oil firm must now hand over confidential internal documents.

The four widows accuse Shell of instigating a deadly crackdown by the military government of the time against peaceful protesters in Ogoniland, in the Niger Delta, the most valuable oil-producing region in Africa.

Nine members of the Movement for the Survival of the Ogoni People, including its leader, Ken Saro-Wiwa, were executed in 1995 by the Nigerian authorities, following a widely discredited trial.

Esther Kiobel, whose husband, Dr Barinem Kiobel, was among the nine executed, said the decision would help exonerate the men.

“We shall prove our case. We have the evidence,” she said. “I wouldn’t be fighting this fight if I didn’t have what it takes. I’ve been fighting for decades.”

It has been a 24-year battle to get even this far. After exhausting all legal recourse in Nigeria, Kiobel first brought a class action against Shell in New York in 2002, where the US supreme court finally ruled in 2013 that the case had been filed in the wrong jurisdiction. A writ was then brought in The Hague, where the oil multinational is based.

Shell denies all allegations that it was complicit in the deaths of the Ogoni Nine or human rights abuses, but it has acknowledged that it was aware Nigeria’s military was taking action to protect the company’s infrastructure. In 2009, it paid out $15.5m (£11.9m) in an out-of-court settlement to Saro-Wiwa’s family and others, but denied any wrongdoing.

Wednesday’s decision has been heralded by activists as “a vital step towards justice” that sets “an important precedent” for people suffering corporate human rights abuses all over the world.

“Victims of human rights violations find it very hard to hold powerful corporations to account and today’s ruling is significant, not just for these very brave women but for people around the world,” said Mark Dummett, Amnesty International’s head of business and human rights, outside the court.

“The fact that this ruling has clearly said that Shell can be held liable for what happened in the 1990s is a very powerful statement. Shell might now face questioning in a court of law about what they knew. The fact that we are now going to move to the next phase and that these documents are going to be examined and witnesses called, means that we can really get to the heart of what actually transpired between Shell and the Nigerian state.”

In a statement, the Shell Petroleum Development Company of Nigeria Limited said: “We have always denied, in the strongest possible terms, the allegations made in this tragic case and believe the evidence clearly shows that Shell was not responsible for these distressing events. Until we have reviewed the detail of the court’s ruling it would not be appropriate to comment in more detail.”

The court ruled that Shell must hand over any evidence that may show it made payments to people who gave false information to Nigerian officials. Witnesses at the time of the Ogoni Nine trial – who later recanted their testimony and claimed they were bribed with money and job offers – will also be interviewed by the widows’ lawyers.

Lead lawyer Channa Samkalden, from human rights law firm Prakken d’Oliveira, said the ruling promised to have positive ramifications for anyone seeking justice from a major corporation.

“It’s extremely important for our plaintiffs, and also for other victims of corporate human rights abuse, that they get access to courts and justice,” said Samkalden. “At least we’ve reached that stage now and are able to make our case. It’s already a big step towards justice.”

Victoria Bera, who was pregnant when her activist husband Baribor Bera, was arrested, and was later forced to flee with her son to a Benin refugee camp after their home was destroyed by the Nigerian military, said the ruling had brought her some peace.

“I feel relief in my heart that we’re going to get to the bottom of this,” she said. “The witnesses will speak and the truth will come out.”