March 15 (Bloomberg) -- The U.S. Department of Homeland Security has failed to provide adequate leadership to safeguard the domestic food supply from potential contamination by terrorists, a federal audit found.

The post-harvest food chain -- which includes storage, processing, packaging, transportation and sale of products -- is ``highly vulnerable to attack,'' a report by the department's inspector general said, citing experts interviewed by auditors.

Many homeland security officials have underestimated the extent of the threat and given little attention to the issue, according to the 151-page report posted on the DHS Web site.

The report cited ``confusion'' in DHS policies because of ``the absence of a clear leader'' in food protection. It said there is ``limited leadership attention to food defense and critical infrastructure protection.''

The agency, headed by Michael Chertoff, has five different units responsible for protecting the food supply, resulting in conflicting approaches, the report said. DHS hasn't done enough to set priorities among sites in the food chain that need protection, nor has it adequately coordinated with other federal agencies and the private sector, it said.

Some prominent U.S. officials have predicted the possibility of terrorist attacks on the food supply.

Former Secretary of Health and Human Services Tommy Thompson said in December 2004 that ``I, for the life of me, cannot understand why the terrorists have not attacked our food supply because it is so easy to do.''

`Widely Diffuse Nature'

In 2003, the President's Council of Advisors on Science and Technology wrote that ``terrorist acts of a widely diffuse nature such as attacks on the food supply'' could be initiated more often.

DHS has been responsible since January 2004 for overseeing the overall national effort to protect the food and agriculture sectors. It is supposed to work with the private sectors and agencies such as the U.S. Department of Agriculture and the U.S. Food and Drug Administration.

Food products can be deliberately contaminated with chemical, biological or radiological agents, though there have been few known cases. In perhaps the most notable, members of a religious cult poisoned 10 Oregon salad bars with Salmonella bacteria in 1984, resulting in 751 cases of illness.

A top DHS official said the audit was overly negative and neglected the agency's accomplishments. At the same time, he acknowledged that the agency needs a single official accountable for food-protection responsibilities.

``The sector would benefit significantly from more internal and external coordination, and we endorse many of the recommendations,'' DHS Undersecretary George Foresman said in a latter appended to the report.

DHS spokesman Russ Knocke declined comment today.

To contact the reporter on this story: Neil Roland in Washington at nroland@bloomberg.net.

Last Updated: March 15, 2007 16:23 EDT