FRESNO, Calif. (AP) — The Food and Drug Administration's efforts to combat food-borne illness are hampered by infrequent inspections, not enough staff and the failure to implement a program devoted to the safety of fresh produce, according to congressional investigators.

The Government Accountability Office draft report obtained Thursday by The Associated Press also said that only 1 percent of produce imported into the U.S. is inspected, and that the practice of mixing produce from several sources makes it hard to trace contamination.

The findings, to be released today, outraged Sen. Barbara Boxer, a California Democrat who along with Massachusetts Sen. Ted Kennedy called for the investigation after the 2006 E. coli contamination in bagged spinach killed three people, sickened 200 others and cost the leafy greens industry $86 million.

"This report paints a frightening picture of the FDA's fresh produce safety efforts," Boxer said. It "should serve as a wake up call to do more to protect the nation's food supply."

A spokesman for the FDA would not comment until the report was released.