BP PLC (IW 1000/4) agreed Thursday to pay a record $4.5 billion in U.S. fines for the 2010 Gulf of Mexico oil spill and will plead guilty to obstruction and criminal negligence in the deaths of 11 workers.

The company's reputation was ravaged after an April 20, 2010, explosion on the BP-leased Deepwater Horizon rig killed 11 workers and unleashed the biggest marine oil spill in the industry's history.

It took 87 days to cap BP's runaway Macondo well 5,000 feet below the water surface as it spewed some 4.9 million barrels (206 million gallons) of oil into the Gulf of Mexico.

Thursday's settlement does not close the book on the British energy giant's lengthy and complex legal battle over the devastating spill and must still be approved by a federal judge.

BP is also still on the hook for economic damages, including the cost of environmental rehabilitation, and could pay as much as $18 billion in civil penalties.

The massive criminal fine -- which will be paid over six years -- will be relatively easy for BP to absorb. It has a market value of $127 billion and last month hiked its shareholder dividend after posting a bumper third quarter profit of $5.43 billion.