NEW ORLEANS (AP) - A man who worked for BP's cement contractor on the drilling rig that exploded in the Gulf of Mexico in 2010 says he didn't believe the oil giant's employees were risking workers' safety when they didn't follow his recommendations.

Halliburton employee Jesse Gagliano began testifying on Tuesday at a trial to determine what caused the blowout of BP PLC's Macondo well and assign fault to the companies involved.

Mr Gagliano says his relationship with employees for London-based BP deteriorated amid disagreements about how to perform the cement job that ultimately failed to seal the well. But he says he said he never saw a reason to call a halt to the project before the blowout.

Mr Gagliano invoked his Fifth Amendment right against self-incrimination at his 2011 deposition but later agreed to testify at trial.