Industry figures have derided the republishing of "old" evidence linking processed meats to cancer, insisting sales will not be damaged by the negative publicity.

The World Cancer Research Fund continued its long-running campaign against processed meat consumption this week by urging parents not to include ham and other meats in kids' lunchboxes.

But meat industry insiders claimed the report was "nothing new", adding that consumers took little notice of the headlines generated by the campaign.

"People are fed up and don't know what to do with all this information," said Provision Trade Federation director general Clare Cheney.

The WCRF had been recycling the same report for the past 18 months without affecting sales of processed meats, said a Bpex spokesman. "No single food is going to make a massive difference to somebody's chances of developing cancer," he added. "Pork sales are actually showing a slight increase."

Others warned the WCRF's research was inconsistent and premature.

"We need to take a critical look at the evidence and must not put forward recommendations to the public as a whole unless we are absolutely sure of the benefits," said Dr Verner Wheelock, director of food safety and nutrition consultants Verner Wheelock Associates. Researchers should also not take evidence from individual cases and apply them to the whole population, he said.

The WCRF claimed there was "convincing scientific evidence" that eating processed meat increased the risk of bowel cancer, adding that 3,700 cases could be prevented in the UK if everyone ate less than 70g of processed meat or three rashers of bacon a week.

But the FSA stressed that parents shouldn't be put off giving children ham as part of a balanced diet.

"While there is some evidence linking bowel cancer to red and processed meats, there is no evidence that the occasional ham sandwich will increase the risk," it said.