Officials in Vietnam are launching a nationwide census to locate the victims of toxic chemicals such as Agent Orange, used by the United States during the Vietnam War more than twenty years ago.

It's thought that tens of thousands of Vietnamese affected by the chemicals are in need of medical and financial help.

Some of those exposed to the chemicals are known to have contracted cancer, or given birth to deformed, paralysed or mentally retarded children. Correspondents say during a ten-year period at the height of US involvement in the Vietnam War, more than forty million litres of toxic chemicals were used against communist fighters.

Officials say the number of cases related to such chemical exposure are increasing every year.