He announced he had been given the right to take over what was then Zimbabwe's biggest mango farm. Mr Freeth insisted that the minister first go through the correct legal procedures.

The researchers, led by Tony Freeth and Mike G. Edmunds, both of the University of Cardiff, Wales, are reporting the results of their study in Thursday's issue of the journal Nature.

Though no one in the Campbell-Freeth families has been killed, they and their 150 workers have, over the past five years, been subjected to repeated harassment and terrifying intimidation.