Other health agencies, including the World Cancer research Fund, have been saying for years that processed meats are carcinogens, and can cause cancer if eaten in enough quantity.
But the WHO's International Agency for Research on Cancer believes that the meats could cause cancer even when only small quantities are consumed.
One theory is that haem, or heme, a pigment that gives processed meat its colour, may damage the lining of the stomach. Carcinogens could also be created during the processing process when the meat is smoked, cured or salted, or when preservatives are added.
The risk is greatest among people who eat large amounts of meat and very few vegetables, and especially the leafy green variety.
To keep your cancer risk to a minimum, the WCRF recommends that we eat no more than 500 g (1. 1lbs) of cooked red meat a week, which is the equivalent of 700g (1.5 lbs) of raw meat.
Along with processed meats, such as ham, sausages and bacon, red meat includes lamb, pork chops, mince and hamburgers.