The federal judge presiding over BP Plc's Texas refinery blast prosecution stepped down after victims attacked a U.S. plea agreement as “shockingly lenient” and accused the judge of a conflict of interest, according to a report.

The victims' lawyer, David Perry, argued that U.S. District Judge Gray Miller should remove himself since he worked for BP's law firm at the time of the 2005 explosion that killed 15 workers and injured 170 others. Miller subsequently stepped aside, and U.S. District Judge David Hittner has been assigned to the case.

Perry has asked the new judge to award $2 billion for claims related to the 2005 blast instead of the $50 million provided for under the plea deal.

“BP has a prior history of terrible misconduct, and that ought to form the basis” for increasing the fine to the federal maximum of twice the criminal proceeds, said Perry. The victims claim BP earned $1 billion from the plant in the 14 months before the blast.

BP agreed last month to plead guilty to exposing workers to toxic emissions during the Texas City explosion, trying to corner the propane-trading market and spilling 200,000 gallons of oil from corroded Alaskan pipelines. The plea bargain, with combined fines of $373 million, will end BP's federal criminal liability from the blast and the spills.

The $50 million portion of the fine related to the explosion allows BP, Europe's second-largest oil company, to retain profits made by running the plant without necessary safety improvements, workers said in their victim impact statement, filed in Houston federal court. Miller, who was to accept BP's plea Nov. 27, worked for Houston-based Fulbright & Jaworski before being appointed to the bench by President George W. Bush in 2006.

“The plea agreement proposed by the government and the defendant BP Products North America Inc. should be rejected as shockingly lenient and providing preferential treatment to BP,” the workers said. The fine amount “allows BP to retain more than 95 percent of the profit from its criminal conduct.”

The explosion occurred March 23, 2005, when an octane-boosting unit overflowed as it was being restarted following repairs. Gasoline vapors spewed into an inadequate vent system, igniting a blast that destroyed windows five miles away.

BP, based in London, has admitted responsibility for the blast, which generated a record $21 million fine from OSHA and a finding by the U.S. Chemical Safety Board that excessive budget cuts compromised safety. BP said it never intentionally endangered workers.