BP Plc is seeking an initial reduction of 17 percent in the amount of oil that will be used to calculate Clean Water Act penalties for its 2010 oil spill in the Gulf of Mexico.

In a motion filed on Friday ahead of a trial in New Orleans next month, BP said about 833,000 barrels of oil that the U.S. government has acknowledged as "recovered" by the response team should be excluded.

The spill followed a well blowout on April 20, 2010 that killed 11 workers and led to a gusher that spewed oil into the Gulf of Mexico for nearly three months.

While BP said it believes that a 4.9 million-barrel estimate "significantly overstates" the spill's size, apart from the recovered oil, the company recognized this was a matter for the trial scheduled to begin on Feb. 25.

"Today's motion is the first step for BP in making that case," said BP spokesman Scott Dean.

Clean Water Act penalties are assessed on oil that enters the environment and causes harm, according to the legal filing.

BP said that, as a matter of practice, courts rarely assess a Clean Water Act penalty near the full maximum of $1,100 per barrel, citing the case of "United States v. Citgo Petroleum Corp" when it was set at $111 per barrel.

The BP case is In re: Oil Spill by the Oil Rig "Deepwater Horizon" in the Gulf of Mexico, on April 20, 2010, No. 10-md-02179, in the U.S. District Court, Eastern District of Louisiana.

 (Reuters, edited by Topco)