The crew of the Deepwater Horizon had a number of warning signs extending over five hours that conditions were worsening deep underwater before the oilrig exploded in the Gulf on April 20, BP's own investigators told a House inquiry into the cause of the deadly accident.

Details of BP's internal investigation provide fresh information about the extent of failures on the ill-fated rig, but the oil company's inquiry skirts the central question: why were those warnings ignored?

The apparent complacency of the BP crew comes as the Obama administration wrestles with the scope of possible new regulations on deepwater drilling and as a White House ordered inquiry is poised to release its findings on the explosion and spill.

Meanwhile, BP is set to attempt Wednesday to staunch the leak a mile below the surface. Oil company officials say the odds of success are 60 to 70 percent.

In its report to Congress, BP said crews noticed unusual pressure and fluid readings that should have alerted them not to remove heavy drilling lubricants known as "mud" from the well — a move that apparently allowed a sudden upwelling of gas that led to the explosion and sinking of the rig about 50 miles from the Louisiana shoreline.

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