Factbox - U.S. energy regulator FERC's biggest civil penalties

(Reuters) - A U.S. judge on Thursday found that BP Plc (BP.L) manipulated the natural gas market in 2008, as alleged by the U.S. energy regulator, but did not address a proposed $28 million (18 million pounds) fine or any other penalties.

The administrative law judge's decision upheld the Federal Energy Regulatory Commission's previous charges that BP's trading activities in Texas violated the Natural Gas Act.

FERC in August 2013 ordered BP to explain why it should not have to pay the fine and disgorge $800,000 plus interest. BP has disputed FERC's allegations.

FERC has issued almost $1.2 billion in fines since the U.S. Energy Policy Act of 2005 significantly increased the penalties it can impose, boosting them to $1 million per day per violation from a prior cap of $10,000 per day.

(Reporting by Scott DiSavino; Editing by Lisa Shumaker)