Documents have emerged which detail for the first time the potentially lethal nature of toxic waste dumped by British-based oil traders in one of west Africa's poorest countries.

More than 30,000 people from Ivory Coast claim they were affected by the ­poisonous cocktail and are currently bringing Britain's biggest-ever group lawsuit against the company, Trafigura.

The firm chartered the ship, Probo Koala, which transported the cargo to Ivory Coast in 2006.

An official Dutch analysis of samples of the waste carried by the Probo Koala indicate that it contained approximately 2 tonnes of hydrogen sulphide, a killer gas with a characteristic smell of rotten eggs.