US meat giant ConAgra Foods is at the centre of the second largest ground beef recall in the US after recalling nearly 19 million pounds on the suspicion that it is contaminated with the deadly E. coli 0157:H7 bacteria.

The news expands a previous recall announced by ConAgra at the end of last month. At least 22 people have fallen ill after eating the contaminated beef, and they are mostly in Colorado. The meat was produced at the company's Greeley, Colorado, plant between 12 April and 11 July, according to the US Department of Agriculture (USDA).

It was sold in various stores and packages, ranging from the 16oz packages with grocery store branding to the generic 60lb "chubs" used by supermarkets to produce smaller packages. The USDA said however that all the recalled meat was labelled with "EST. 969" inside a USDA seal of inspection.

The major supermarket chains have scrambled to withdraw the affected products. Safeway said that about 500 stores in northern California, Denver and Chicago have been affected.

Consumer groups have slammed the USDA for doing more to protect big business above public health, after it admitted waiting ten days to notify ConAgra after federal meat inspectors detected E-coli at the firm's plant on 10 June. In future, said the USDA, inspectors will inform companies before investigations are complete.

USDA Undersecretary Elsa Murano admitted: "We have no way of knowing for sure how much (beef) is in consumers' hands." Consumers who still have any of the meat in the recall are being urged to discard it or call ConAgra at 888-742-0467.

The largest ground beef recall was made in 1997, when Hudson Beef recalled 35 million pounds of meat because of E-coli contamination.