The World Health Organisation says nearly one-third of the world's population carries the bacterium which causes the disease, tuberculosis, with the greatest concentration in African countries.

One in ten people carrying the bacterium is likely to develop the disease.

The World Health Organisation -- in what it calls the most exhaustive study of tuberculosis ever compiled -- says the problem is poor health-care in many countries, meaning prevention and treatment programmes are not always carried out.

Drug-resistant strains of the disease, it says, only affect a few places. Nine out of the top-ten countries suffering tuberculosis are in Africa, which the report links with the spread of the H-I-V virus which can lead to AIDS, and which affects the immune system.