Trafigura, the oil-trading company at the centre of the scandal caused by the dumping of tons of toxic waste in one of the world's poorest countries, could be prosecuted for murder after a dossier of evidence was submitted to a court in the Netherlands yesterday, alleging that the sludge caused deaths and serious injuries.

A complaint filed by Greenpeace Netherlands calls for a Dutch prosecution arising from Trafigura's actions in July 2006 – when a chartered tanker carrying the contaminated waste arrived in Amsterdam – to be widened to include events in Ivory Coast a month later which caused thousands of people to fall ill after tons of the foul-smelling slurry was dumped in the port of Abidjan.

The campaigning group wants Dutch courts to order public prosecutors to bring charges of murder, manslaughter, negligence and conspiracy against the London-based commodities giant, which has vigorously denied any knowledge of the fly-tipping of the waste by an Ivorian sub-contractor in August 2006.

Download the new Independent Premium app Sharing the full story, not just the headlines

Emails between Trafigura employees submitted to the court in The Hague are claimed by Greenpeace to show that the company knew the waste – described in one internal memo as "the shit" – was potentially hazardous and could not be exported outside the European Union. Trafigura insists that its managers sought at all times to dispose lawfully of the "slops" on board its chartered tanker, the Probo Koala.

Trafigura, which last year had a turnover of $73bn (£44bn, equivalent to twice the GDP of Ivory Coast), has agreed to a multimillion-pound payout to settle Britain's largest group lawsuit, brought by 30,000 Abidjan residents who fell ill after breathing in fumes from the sludge.

The settlement of the High Court case, expected to be finalised within weeks, concerns claims by victims who suffered short-term illnesses. But it does not apply to allegations, which will now not be tested in the British courts, that the dumped waste caused more serious problems, including deaths, miscarriages and birth defects.

Trafigura has fought a three-year battle, engaging PR consultants and libel lawyers to dispute critical reporting of the incident, and insists that the waste could not have caused the serious injuries alleged. A United Nations report this week stated that there seemed to be "prima facie evidence" that up to a dozen deaths in Abidjan were linked to the sludge.

The oil trader, the third-largest of its kind in the world, is already being prosecuted in the Netherlands over claims that it breached Dutch and European laws by misdeclaring the nature of the sludge on the Probo Koala when it arrived in Amsterdam, and by subsequently taking the waste outside EU borders. A Greenpeace spokesman said: "The emails show that Trafigura employees knew the waste would be difficult to deal with and were desperate to find someone who would take it off their hands.

"There are now no legal proceedings which will test the claims that as well as making thousands of people in Ivory Coast sick, the waste was also responsible for deaths and other serious injuries of innocent people. We are asking the Dutch courts to change that."

The contaminated sludge – its composition is disputed by Trafigura and opponents – was the by-product of deals struck by the company's traders in 2005 and 2006 to buy a cheap and dirty oil known as "coker naptha" from a Mexican refinery and extract clean fuel from it by adding a mixture of caustic soda and a catalyst. Emails show Trafigura expected to make a profit of $7m (£4m) from each cargo, despite the fact that "caustic washes are banned in most countries due to the hazardous nature of the waste". This do-it-yourself process was performed in or about April 2006 on board the Probo Koala while it was anchored off Gibraltar. The resulting waste arrived in Abidjan on 19 August 2006 and was unloaded from the tanker into trucks hired by Compagnie Tommy, the sub-contractor employed by Trafigura's shipping agent.

It was then dumped at 18 sites, including drains and lagoons, around the sprawling city, leading to a flood of victims complaining of symptoms including sickness, diarrhoea and breathing difficulties. Autopsy reports included in the Greenpeace dossier suggest that the bodies of 12 people who died in Abidjan showed high levels of hydrogen sulphide, a poisonous gas which campaigners claim was present in the waste. Trafigura insists the gas could not have been emitted by the sludge.

In a statement, the company accused Greenpeace of a "wholly selective interpretation" of a small number of emails containing "trader-speak" which could not be taken literally. It added: "More importantly, on a proper analysis of all the material and of what in fact happened, it is clear that the responsible individuals at Trafigura sought at all times to ensure that the slops were disposed of lawfully.

"Greenpeace Netherlands' unfounded accusations are utterly rejected by Trafigura. It is deeply regrettable that Greenpeace has chosen to make a number of serious and unfounded remarks, without any regard to the available scientific evidence or to statements made by Trafigura based on detailed analysis by independent experts."