But the researchers, from Leeds University, found no link between eating poultry or offal and an increased risk of breast cancer.

Cancer campaigners said the research was interesting, but said many factors could increase the risk of developing the disease, not only diet.

Professor Janet Cade, who led the research, said there was growing evidence linking red-meat consumption to bowel and pancreatic cancers.

But studies linking the meat to breast cancer had produced conflicting results.

The latest study, published in the British Journal of Cancer, found that post-menopausal women eating a daily portion of more than 57g of red meat had a 56% greater risk of breast cancer.

But those who ate the largest amounts of processed meat -- more than 20g a day -- faced a 64% greater risk compared to those eating none.

Even those with low consumption -- less than 10g -- had a 48% increased risk of cancer.

The researchers also found a higher risk in pre-menopausal women, but they said it was not statistically significant.

The reasons for the link are also unclear, although a high intake of fat in the diet has been linked to a greater risk of a range of cancers.

Cade said, "There are several mechanisms whereby meat intake may contribute to breast-cancer risk.

"Meat and, in particular, processed meats, can be a rich source of saturated fat."

The link could also be due to the way meat is preserved or cooked, the researchers said.

Professor Cade said, "The message here is simple. All women should think carefully about their consumption of red meat."

Dr Alexis Willett, senior policy officer for Breakthrough Breast Cancer, said the study was "interesting" but, because people ate a variety of foods, it was difficult to separate out the specific effect of red meat on breast-cancer risk.

She added, "Previous research studying red meat and breast- cancer risk have been inconclusive.

"However, experts estimate that approximately 30 per cent of all cancers in western countries are linked to diet."

Henry Scowcroft, from Cancer Research UK, said, "The links between meat consumption, fat intake and breast-cancer risk are still being studied.

"Our best dietary advice to women worried about their breast-cancer risk is to maintain a healthy bodyweight by taking regular exercise and avoiding large regular portions of fatty foods like red and processed meat and excess alcohol."

From the April 9, 2007, Prepared Foods e-Flash