WASHINGTON (AP) - Investigators with the president's oil spill commission have found that tests performed before the deadly blowout of a BP oil well in the Gulf of Mexico should have raised doubts about the cement used to seal the well. But the company and its cementing contractor failed to act on the information.

The finding from the panel's staff appears to conflict with statements made by Halliburton Co., which has said tests showed the cement mix was stable. The cement's failure to prevent oil and gas from entering the well has been identified as one of the causes of the accident.

The panel says only one test of four by Halliburton on the cement's stability showed that it would hold. But the single successful test was not shared with BP, and may not have been known by Halliburton, before the cement was pumped.