WASHINGTON - Government programs aimed at keeping weapons of mass destruction from entering U.S. ports are flawed and could actually be counterproductive, congressional investigators have found.

Reports by the Government Accountability Office, Congress' investigative arm, faulted both the Customs-Trade Partnership Against Terrorism, or C-TPAT, and the Container Security Initiative, or CSI. Both programs were adopted after the Sept. 11, 2001, attacks to inspect shipments before they reached U.S. ports.

The Senate permanent subcommittee on investigations, which requested the reports, will hold a hearing on the findings today.

In an interview with The Associated Press on Wednesday, Customs and Border Protection Commissioner Robert C. Bonner said that while some security gaps remain, "we've always viewed these as dynamic programs, and so we are in the process of improving them and making them better."

C-TPAT allows international shippers to get quicker clearance through customs in exchange for voluntary security measures. But the GAO said U.S. Customs and Border Protection's vetting process was not thorough enough. It found that only about 10 percent of the certified members had been validated through an actual physical inspection by the agency; the rest had been certified through paperwork applications.

The lack of a reliable validation process, the GAO wrote, "potentially weakens the overall effectiveness of the other control mechanisms in meeting (the agency's) fundamental responsibility to ensure security of all cargo entering the United States."

The CSI program posts U.S. customs inspectors in 36 foreign ports to look for suspicious cargo, which they then refer to the host country for further inspection. But the GAO found that of those, 28 percent were not inspected by the host country.

In addition, GAO investigators found that 35 percent of shipments from these ports were not subject to inspection, and also concluded that the program lacked minimal technical requirements for inspection.

Given those shortcomings, the GAO wrote, the agency "has limited assurance that inspections conducted under CSI are effective at detecting and identifying terrorist weapons of mass destruction."

The Senate permanent subcommittee on investigations conducted its own review, visiting eight foreign ports, ranging from Hong Kong to Hamburg, Germany. The subcommittee concluded that only 17.5 percent of high-risk cargo from these ports is inspected overseas, and less than 1 percent of all containers are inspected.

"We have folks here who have the right intentions," said the subcommittee chairman, Minnesota Republican Norm Coleman. "But rather than making it harder for folks with evil intentions to do harm to this country, we have in place a system that creates the potential for greater vulnerability."

Bonner said the country faces "the potential for a terror attack and exploitation of our primary systems in trade and movement of goods. And we needed to take action. We viewed this with a sense of urgency, and the bottom line today is that these programs are working, and we are safer today because of them."

Coleman told the AP Wednesday that the agency has taken steps over the past month to address some of the GAO concerns, but said more needs to be done to strengthen port security.

AP Writer Lara Jakes Jordan contributed to this story.