'BP officials knew about a problem on a crucial well safety device at least three months before the catastrophic April 20 explosion in the Gulf of Mexico but failed to repair it, according to testimony Tuesday from the company's well manager.

Ronald Sepulvado testified that he was aware of a leak on a control pod atop the well's blowout preventer and notified his supervisor in Houston about the problem, which Sepulvado didn't consider crucial. The 450-ton hydraulic device, designed to prevent gas or oil from blasting out of the drill hole, failed during the disaster, which killed 11 men on the Deepwater Horizon rig and set off the worst offshore oil spill in U.S. history.

Investigators said BP did not disclose the matter to the appropriate federal agency and failed to suspend drilling operations until the problem was resolved, as required by law.'

Read more: BP Testimony: Officials Knew of Key Safety Problem on Rig