The Deepwater Horizon oil spill off the US coast in 2010 nearly ruined BP, the company's chief executive has said.
Speaking to ex-BP boss Lord Brown, who was guest editing BBC Radio 4's Today programme, Bob Dudley said the spill was a "tragic accident" that shook the company "to its core".
"Sometimes it takes a near death experience to radically change a company. It was a forced focussing down of what we do, it was this is what we need to do to survive," he added.
The spill was one of the largest environmental disasters in the US, and resulted in a total pre-tax charge for the spill of around $53.8bn.
The rig exploded on 20 April 2010, killing 11 workers and spewed over three million barrels of oil into the Gulf of Mexico.
In October the oil giant was ordered to shell out more than $20bn (£13.2bn) in fines to resolve nearly all claims from its deadly Gulf of Mexico oil spill five years ago, brought by the government and the five states - Louisiana, Texas, Alabama and Florida - that were affected by the spill.