BP Oil Disaster: Pre-Spill Tests 'Showed Cement Flaw'

Both BP, which owned the well, and Halliburton, the contractor responsible for the cement, were aware of tests showing it was unstable, they said.

Halliburton has denied the claims, saying the tests were invalid as they were on a different kind of cement.

The 20 April blowout led to the worst environmental disaster in US history.

Eleven workers on the Deepwater Horizon drilling rig were killed by an explosion which followed, and hundreds of miles of coast were polluted. Read the full report here.

Source: BBC News, US & Canada.