Trafigura refuses to aid fire inquiry

Trafigura, the British oil trading giant which agreed to pay £30m to the victims of one of Africa's worst pollution disasters, has failed to co-operate with an investigation into an explosion in a Norwegian fjord involving waste from one of its ships, The Independent can reveal.

Hundreds of residents of the Norwegian village of Slovag fell ill in May 2007 when a huge tank holding waste from low-quality oil processed on behalf of Trafigura caught fire and exploded, leading to one of the worst pollution incidents in Norway's history as a cloud of sulphurous smoke rose over the surrounding area.

A prosecution of three individuals linked to Vest Tank, the Norwegian company which ran the processing operation on Norway's west coast, is due to begin in November and will hear evidence of how Trafigura sent six shipments totalling 150,000 tonnes of cheap and dirty coker gasoline to Slovag in 2006 and 2007.

Trafigura is not being prosecuted in Norway in relation to the explosion and there is no suggestion it was responsible for the disaster. But Norwegian police told The Independent that the company has refused repeated requests to interview a number of its employees involved with the shipments.

Tarjei Istad, a senior investigator from Norway's national economic and environmental crime force Okokrim, said: "As a result of our investigation [into the 2007 explosion] we are interested in speaking to some Trafigura employees who were on the side of the business that dealt with Vest Tank. This has not happened. Trafigura have attempted to set conditions before they decide whether to allow these interviews. Our understanding is that Trafigura is not willing to allow these interviews. We are satisfied we have sufficient evidence from elsewhere, but it is a pity that Trafigura will not agree to co-operate."

The explosion on 24 May 2007 took place after Vest Tank struck a deal with traders in Trafigura's London offices to treat its coker gasoline – bought at bargain prices from Mexico – with caustic soda, so as to create a low-octane petrol. The resulting substance was further treated at a refinery in Estonia to create a fuel with a high sulphur content, which meant it could not be sold in Europe but was permitted for sale in Africa.

The Norwegian authorities allege Vest Tank did not hold the correct permits to carry out the caustic soda "washing" of Trafigura's gasoline or to process the waste from the procedure which contained mercaptan sulphur. Vest Tank insists it did have permission.

The Slovag explosion took place nine months after waste from the Probo Koala, a tanker chartered by Trafigura, was illegally dumped in the Ivory Coast port of Abidjan by a sub-contractor. The foul-smelling waste was produced while the Probo Koala was anchored off Gibraltar conducting the same caustic soda treatment on a cargo of coker gasoline as that used in Norway. Trafigura insists the waste was dumped in Abidjan without its knowledge.

The first Slovag residents knew of the process being conducted at Vest Tank's terminal was when a plume of mercaptan-laden smoke rose into the air. Norwegian authorities said hundreds of people fell ill.

A spokesman for Trafigura said it would not comment on a continuing investigation, adding: "Trafigura complied fully with the relevant regulations in its dealings with Vest Tank's owners."