Amnesty International has obtained internal documents pointing to complicity by Royal Dutch Shell in crimes committed by the Nigerian military during the 1990s.

The rights group released a report on Tuesday that alleges that the British-Dutch oil giant and the Nigerian government operated as business partners, having regular meetings to discuss the protection of their interests.

At the time, protests by the Ogoni people of southeastern Nigeria were taking place in response to years of oil spills at Shell facilities, which devastated their environment.

Documents obtained by Amnesty show that on October 29, 1990, Shell requested "security protection" to subdue peaceful demonstrations. Over the next two days, police attacked an Ogoni village with guns and grenades, killing at least 80 people, and burning almost 600 homes.

Nevertheless, Shell continued to ask for military help in the following years, Amnesty said.

The allegations have been known for some time, but thus far had not been substantiated with internal documents.

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The rights group has gone through thousands of pages of Shell's documents and testimony statements. The files show that Shell repeatedly urged the Nigerian army to take action against protests by the Ogoni community.

According to the organisation, Shell called for military support from senior officials, even after the military forces had killed, tortured or raped many demonstrators.

The directors of Shell in The Hague and London were aware of this, according to Amnesty.

In a statement to Al Jazeera, Shell in Nigeria denied it was involved in human rights violations.

"We have always denied, in the strongest possible terms, the allegations made in this tragic case," the statement read.

"Amnesty International's allegations are false and without merit. Shell did not collude with the authorities to suppress community unrest and in no way encouraged or advocated any act of violence in Nigeria," the statement added.

Amnesty has compiled a case to start a lawsuit against Royal Dutch Shell.