The duke's concern about pesticides getting into the food chain was sparked by the discovery of 16 dead pheasants on the royal estate at Sandringham in 1991. Tests showed they had been poisoned after eating newly sown wheat treated with organo-phosphates. As a result, Prince Philip and the estate have pressed the Government to explain why it has sanctioned the use of the chemicals.
Buckingham Palace spokesman David Tuck said the dukewas "not just worried about the pheasants, but more about the impact these substances have on wildlife in general".
Organo-phosphates are used widely in crop sprays and sheep dips, as well as in flea collars and head-lice shampoos. However, there has been growing concern over their effect on the health of both wildlife and humans.