Two BP employees are facing manslaughter charges over the 2010 oil spill in the Gulf of Mexico, according to reports.
The British oil giant is also said to have agreed to pay a criminal penalty amounting to billions of dollars over the Deepwater Horizon disaster.
The spill killed 11 people and set off a spill that continued for 87 days, fouling large areas of the southern coast of the US.
A source speaking to the AP news agency said BP will plead guilty to obstruction for lying to Congress about how much oil was pouring out of the ruptured well.
The impending agreement covers all of the United States' Department of Justice (DoJ) and Securities & Exchange Commission (SEC) claims against BP in relation to the blowout.
The proposed settlement will not include civil claims under the Clean Water Act and other legislation, pending private civil claims and state claims for economic loss.
In a statement earlier on Thursday BP said "no final agreement has yet been reached" and that any deal would still be subject to court approvals.
The settlement was expected to dwarf the largest previous corporate criminal penalty assessed by the DoJ - the $1.2bn (£750m) fine imposed on drug-maker Pfizer in 2009.
BP has set aside $37.2bn (£23.4bn) to cover its liabilities from the incident, but the company has said the final cost is uncertain.
BP also recently announced it expects to make the final payment this year to a $20bn (£12.6bn) trust fund to cover damage from the blowout.
In March, BP announced a settlement with multiple claimants for medical and economic losses, which is estimated to cost $7.8bn (£4.9bn).
The spill exposed lax US government oversight and led to a temporary ban on deepwater drilling while officials and the oil industry studied the risks, worked to make it safer and developed better disaster plans.
BP chief executive Tony Hayward stepped down after the company's repeated gaffes, including his statement at the height of the crisis: "I'd like my life back."
BP's environmentally friendly image was tarnished, and independent fuel station owners who fly the BP flag claimed they lost business from customers who were upset over the spill.