A new report has called on the British government to investigate the multinational company Trafigura for its alleged role in dumping toxic waste in Ivory Coast in 2006.

Ivorian authorities say that at least 15 people died and tens of thousands of others were sickened by the dumping of waste by a ship chartered by multinational oil trader Trafigura.

A three-year-long investigation by Amnesty International and Greenpeace published on Tuesday points to "clear evidence that at least part of the decision-making process on export of the waste from Europe and delivery to Abidjan emanated from London", making UK prosecutions feasible.

The report calls for the UK to undertake criminal investigations against Trafigura.

It also urges Ivory Coast to review a 2007 decision that gave Trafigura immunity from prosecution on Ivorian soil, and to probe how compensation from an out-of-court settlement in the UK was allowed to be misappropriated.

More than 100,000 people sought medical treatment in the first five months after the waste was dumped in Abidjan.

'Caustic Washing'

A national commission of inquiry reported 15 deaths, though an Ivorian court put that number at 17.

Trafigura has disputed those figures, saying the waste could only have caused "low level flulike symptoms and anxiety."

The British government has said it would be inappropriate for the UK to launch an investigation because the vessel involved was not registered in the UK and the waste wasn't loaded in or originating from the UK.

"We condemn incidents such as occurred in Abidjan where toxic waste was dumped, with such devastating effects on human life and the environment," a spokesman from the Department for Environment, Food and Rural Affairs said.

The report describes how Trafigura purchased large amounts of an unrefined gasoline called coker naphtha, then subjected it to a refining process known as "caustic washing", which is known to create hazardous waste.

The caustic washing was initially carried out on land in the United Arab Emirates and Tunisia, but Tunisian authorities suspended the process in April 2006 after workers became ill, and the rest of the process was carried out at sea, according to the report.

Although the case has received much attention, the new report contends that Trafigura's role in the dumping ``has never been subject to a full court proceeding.