HOUSTON (AP) — Attorneys for victims of the 2005 explosion at BP PLC's Texas City refinery contend the oil giant's fine could be as much as $3.2 billion, dwarfing the $50 million being proposed in a plea agreement.

Attorneys said the fine should be at least $400 million.

The proposed fines were included in court documents filed by victims' attorneys last week at the request of a federal judge who is deciding whether to accept a plea deal from BP.

The agreement proposes that BP plead guilty to a violation of the Clean Air Act and pay a $50 million fine for its criminal conduct in the blast, which killed 15 people and injured more than 170 others. The company would also be on probation for three years.

Plant manager Keith Casey formally entered the guilty plea on behalf of the company earlier this month. The plea was part of an October agreement by BP to pay $373 million to settle various criminal and civil charges.

But blast victims' attorneys asked U.S. District Judge Lee Rosenthal to reject the deal, arguing the fine was too low and the deal didn't provide for an independent monitor who would report on whether BP was meeting its safety obligations. They also criticized prosecutors for not consulting victims while the deal was being put together.