The U.S. Justice Department is expected to seek indictments of up to four former BP traders as early as Thursday, the Wall Street Journal reported in its online edition.
The indictments are expected in federal district court in Chicago, the Journal reported, citing people people familiar with the case.
BP could not be reached for immediate comment.
The indictments are expected to be brought against former members of BP's propane-trading desk, and will come on the same day that the Justice Department and federal market and environmental regulators are expected to announce that BP has agreed to pay hundreds of millions of dollars to settle criminal and civil probes into a fatal refinery explosion and alleged market manipulation, the Journal said.
On Wednesday, the chairman of the powerful Energy and Commerce Committee in the U.S. House of Representatives said the committee will probe whether the U.S. government extracted sufficient penalties from London-based BP for allegedly manipulating U.S. propane markets.
BP has agreed to pay $303 million to settle civil price-fixing charges brought by federal investigators and "in light of this settlement, the Energy and Commerce Committee will investigate whether government agencies acted appropriately during pricing negotiations with BP," said Rep. John Dingell of Michigan, the committee's chairman.
Dingell's committee has in the past probed a series of mishaps at BP including a leaky pipeline in Alaska to a deadly explosion at a Texas refinery in 2005.