BP Plc paid almost $24.4 million to the U.S. Treasury to cover allegations company traders manipulated natural gas markets in 2008, but is still challenging the fine in court, U.S. energy regulators said in a filing.

The U.S. Federal Energy Regulatory Commission (FERC) alleged BP violated the Natural Gas Act by manipulating the next-day gas market at Houston Ship Channel from mid-September through Nov. 30, 2008.

FERC said in a filing late Jan. 5 that BP paid the fine on Dec. 28 but noted the company said it intends to seek review in the U.S. Court of Appeals for the Fifth Circuit.

"BP maintains that our natural gas traders did not engage in market manipulation," said a spokesperson for BP, noting "We will appeal this decision to the Fifth Circuit."

The case dates to actions taken by BP traders to take advantage of market dislocations around the time Hurricane Ike smashed into the Houston area in September 2008. FERC's Office of Enforcement alleged BP traders made uneconomic physical gas sales to suppress the Houston Ship Channel Gas Daily index and boost the value of BP's financial position.