The trial opened in Ivory Coast on Monday of 12 people charged with involvement in a 2006 toxic waste scandal which killed 17 Ivorians and poisoned thousands.
Nine of the 12 were in court to face a raft of charges including poisoning, complicity to poison and breaking environmental and public safety laws.
The accused include the boss of the Ivorian company which dumped the waste at several public sites, the contamination from which forced more than 100,000 people to seek medical help.
However, none of the directors of Trafigura, the Dutch multinational which operated the ship which brought the waste to Ivory Coast, will face trial.
Trafigura escaped prosecution after reaching a 152-million-euro (215-million-dollar) settlement with the Ivorian government in February last year in return for indemnity against prosecution. The company has never admitted liability.
The incidents date from August 2006 when truck tankers hired by Salomon Ugborugbo, the director general of Ivorian company Tommy, dumped more than 500 cubic metres of waste "slops" from the Panamanian-registered cargo ship, the Probo Koala, at public sites across Abidjan.
The so called slops were a mix of petroleum residues, sulphur and caustic soda which had accumulated in the ship.
Exposure to the waste caused respiratory difficulties, nausea and other medical problems among the local population.
Ugoborugbo is charged with poisoning, while six others are accused of complicity, including the former head of Abidjan's port authority, two shipping agents employed by Trafigura to oversee the Probo Koala's sojourn in Abidjan, amd three customs officials who supervised the pumping out of the ship's slops.
Five others, including the transport ministry official responsible for Abdijan port, are charged with breaking environmental and public safety laws.
The accused face life imprisonment if convicted.
The trial got underway shortly before midday (1200 GMT), after a delay of almost three hours. But the long-awaited hearing was adjourned amid some confusion after only 75 minutes.
Defence lawyers condemned the absence of people they deemed key witnesses in the case, including an official of local Trafigura subsidiary, Puma Energy, which was officially cleared by a court in March along with the parent company.
They also protested they were unable to obtain some of the prosecution documents, and contested the right of the Ivorian state to be a civil party to the case.
The lawyer for Ugborugbo, the main accused, refused to represent his client further as part of the protest -- but changed tack after the senior judge said all documents pertinent to the defence would be handed over.
Three of the accused, a port agent and two garage operators, also failed to turn up for the trial.
The hearing was finally adjourned for the day at 1640 GMT, with its resumption scheduled for Wednesday as Tuesday has been declared a public holiday because of the end of the Muslim holy month of Ramadan.
The case is being held in the Abdijan assises court, which has not met since the west African country's political unrest in 2002.
The trial is expected to last around two weeks.
As of the end of last year, Ivory Coast had paid 31.5 million euros to about half the estimated people poisoned.
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