HOUSTON - Lawyers will return to a federal court in New Orleans Monday to debate whether BP's efforts to stem an oil spill from its Macondo well blowout were adequate and how much oil was released.

Billions of dollars in federal fines will be at stake in this second phase of a complex trial aimed at determining the liability of BP, Anadarko Petroleum Corp., which owned 10 percent of the Macondo well, and their drilling partners, according to The Times-Picayune on Friday.

The nearly two-month first phase of the trial, which ended in April, focused on the liability of BP and its drilling partners for actions they took while the well was being drilled, through April 22, 2010, when the rig ship sank.

The second phase covered the actions of BP and its partners to stop the flow of oil between April 22 and July 15, 2010, when the well was permanently capped, the report said.

In arguments filed in advance of the trial, BP says 2.45 million barrels of oil were released into the Gulf while Justice Department attorneys contend the amount of oil released was 4.2 million barrels.

BP's estimate would result in maximum fines of 2.7 billion dollars for simple negligence, or 10.5 billion dollars if the company committed gross negligence.

In contrast, the government's estimate would result in maximum fines of 4.6 billion dollars for simple negligence or 18 billion dollars for gross negligence, the report said.

On April 20, 2010, BP's Deepwater Horizon drill platform caught fire and exploded, killing 11 workers and triggering one of the worst environmental disasters in the country's history.