The record fine imposed on BP over the 2010 rig explosion and oil spill is a small price to pay for the worst ecological disaster in US history, victims and environmental groups say.
BP agreed on Thursday to pay $US4.5 billion ($A4.38 billion) in US fines for the Gulf of Mexico oil spill and pleaded guilty to 14 counts, including felony manslaughter, in the deaths of 11 workers in the offshore rig blast that caused the disaster.
Stephen Stone, who was working aboard the BP-leased Deepwater Horizon when the explosion tore through the rig on April 20, 2010, welcomed the settlement, but said the blame extended to Transocean, which was operating the rig for BP.
'We have yet to see any serious effort on BP or Transocean's part to come to any resolution,' Stone said.
'I hope that people do not forget that there are still many families who are being ignored by these people despite what their public relations department says.'
It took 87 days to cap BP's runaway Macondo well 1,500 metres below the water surface as it spewed some 4.9 million barrels of oil into the Gulf of Mexico and blackened beaches in five states.
US Attorney General Eric Holder said he hoped the settlements would bring some 'comfort as to why those brave people lost their lives, but at the end of the day we can't bring them back.'
He put BP on notice that its legal troubles are far from over, saying: 'Our criminal investigation remains ongoing.'
He also noted the Justice Department had 'failed to resolve' a civil case to determine how much BP should pay in environmental fines, which could amount to as much as $US18 billion ($A17.5 billion) if gross negligence is found.
'We're looking forward to the trial - which is scheduled to begin in February of next year - in which we intend to prove that BP was grossly negligent in causing the oil spill,' Holder told a press conference.
BP apologised for its role in the spill but vowed to continue fighting claims of negligence, insisting that Transocean and Halliburton - which was responsible for the well's faulty cement job - share blame for the disaster.
Earlier this year, BP reached an agreement to settle claims from fishermen and others affected by the spill for $US7.8 billion, but it must be approved by a federal judge.
Not everyone was pleased with the deal announced on Thursday, with critics pointing out that the $US4.5 billion - to be paid out over six years - is less than the company's third quarter profits from this year alone.
'This fine amounts to a rounding error for a corporation the size of BP,' Greenpeace senior investigator Mark Floegel said.
'Nothing in this proposed settlement gives any oil company incentive to be more careful in future operations. Cutting corners and skimping on safety will still be the rule of the day,' he said.
Tyson Slocum, director of Public Citizen's Energy Program, said the settlement would do little to punish or deter BP or other major oil firms.
'Nothing in this settlement stops BP from continuing to get federal contracts and leases,' he said.
'BP will earn more in annual federal contracts than it will pay in penalties as a result of this. That's appalling.'
But Frances Beinecke, head of the Natural Resources Defence Council, said the settlement was 'an important first step in holding BP accountable.'
'What we hope it does is send a signal to Big Oil that unrelenting irresponsibility will no longer be tolerated,' she said.
'Human life, devastated communities and destroyed resources should never be the cost of doing business.'