The US Department of Agriculture (USDA) is purchasing meat from processing plants that have regularly violated food safety rules in a bid to procure the 300 million pounds of frozen beef requirement of the National School Lunch Program.

The plants producing the meat for the USDA violate critical safety regulations at a higher rate than the industry average, according to an analysis of USDA data conducted by the Chicago Tribune.

The programme was launched in 1946 in a bid to provide students with nutritious meals while bolstering the US agricultural markets.

USDA spokesman Kevin Herglotz insisted to the newspaper: "We've seen improvements in our food safety system and inspection systems.

"It's moving in the right direction [and] we need to continue to make sure we're using the best available science and strengthening the program."

The analysis does raise questions, however, as to how able the USDA is to procure low-cost food for social projects and simultaneously ensure that it is produced to a high quality. Industry officials maintain that on several occasions, the government has negotiated contracts with beef producers that subsequently failed three rounds of salmonella tests, rather than shutting them down.

The most potent example of this is the embarrassing Supreme Beef case, which continued to supply meat due to a court ruling despite failing three consecutive salmonella tests. Another plant with repeated violations is Ocala, Florida-based Bauer Meat Co., which was forced to undergo a massive product recall while selling US$38.7m worth of meat to the programme.

The USDA has rejected growing amounts of beef for the programme on the grounds that it has failed bacteria tests. According to Tribune findings, for exapmple, from October of this year it rejected 12% of the 34 million pounds of ground beef it had purchased, an increase from the 7% of last year.

Experts in food safety have noted that while higher violation rates are concerning, the companies involved may not necessarily be producing contaminated food; the violations could refer to other problems such as record-keeping problems.