The government allowed state-inspected meat plants to operate despite finding soot-like material on pig carcasses and old meat residues on cutting boards, according to a report made public Thursday.

The findings come amid efforts in Congress to let state-inspected plants sell meat anywhere in the United States. Only federally inspected plants can ship meat across state lines or to foreign countries.

A consumer group said Congress should drop the effort and warned people to beware of state-inspected meat. The National Association of State Departments of Agriculture said state plants meet or exceed federal rules.

The audit by the Agriculture Department's inspector general faulted the department, which oversees state inspection programs, for weaknesses in the review process.

Auditors described violations at Mississippi plants in 2003, including "soot-like material found on several swine carcasses in cooler" and "cutting boards (deeply scored and stained) contained product residues from previous days' operations."

Despite the problems, the department said the state inspection program was "at least equal to" the federal inspection program, a designation that allows states to conduct inspections. If the department decides a state program is not equivalent, the department can take control of inspections at state plants.

The report also cited problems in four other states — Missouri, Wisconsin, Delaware and Minnesota.

Barbara Masters, administrator of the department's Food Safety and Inspection Service, said the department revised system of reviewing the 28 states with programs in 2003 and "continues to strengthen" state inspections.

The audit drew criticism from a food safety advocacy group, Consumer Federation of America, which said people were placed at risk by the continued operation of plants with violations.

"In the midst of a foodborne illness outbreak from spinach, the (report) details stomach-wrenching failures by some state inspection programs to meet the most basic sanitation standards and to protect the public from foodborne illness," said Carol Tucker Foreman, the group's director of food policy.

A spokesman for the state agriculture officials' group, Charlie Ingram, said the process worked as intended by giving plants the opportunity to fix problems.

"Many state inspected plants have requirements that are more strict than what USDA requires," Ingram said. "There has never been a documented foodborne illness from state-inspected meat and poultry. This is not a food safety issue. This is a marketing, small-business, rural-development issue."

The group has been lobbying Congress to allow interstate shipment of state-inspected meat, a bill sponsored by House Majority Whip Roy Blunt, R-Mo.