WASHINGTON (AP) - Congressional investigators say Social Security is so overwhelmed by disability claims that some officials are awarding benefits without adequately reviewing applications, potentially adding to the program's financial problems as it edges closer to the brink of insolvency.

In more than a quarter of the 300 cases reviewed by congressional staff, decisions to award benefits "failed to properly address insufficient, contradictory or incomplete evidence."

A report by the Republican staff of the Senate Permanent Subcommittee on Investigations found that in some cases, it appeared that officials struggling to reduce backlogs didn't review all available evidence.

Social Security has been working for years to reduce a huge backlog of disability claims. Spokesman Mark Hinkle said the agency has gotten better at reviewing claims but recognizes there is need for further improvement.