WASHINGTON  A new report finds that the Centers for Disease Control and Prevention did a poor job of screening medical experts for financial conflicts when it hired them to advise the agency on vaccine safety, officials said Thursday.

Most of the experts who served on advisory panels in 2007 to evaluate vaccines for flu and cervical cancer had potential conflicts that were never resolved, the report said. Some were legally barred from considering the issues but did so anyway.

In the report, expected to be released Friday, Daniel R. Levinson, the inspector general of the Department of Health and Human Services, found that the centers failed nearly every time to ensure that the experts adequately filled out forms confirming they were not being paid by companies with an interest in their decisions.

The report found that 64 percent of the advisers had potential conflicts of interest that were never identified or were left unresolved by the centers. Thirteen percent failed to have an appropriate conflicts form on file at the agency at all, which should have barred their participation in the meetings entirely, Mr. Levinson found. And 3 percent voted on matters that ethics officers had already barred them from considering.