"These allegations are without merit and we stand by what we previously disclosed publicly in February 2011 - that BP natural gas traders did not engage in any market manipulation in late 2008," BP spokesman Geoff Morrell said in a statement.
"BP is disappointed that the FERC has brought this action and we will vigorously defend against these allegations."
FERC posted the original allegations in 2011. Monday's order marks the next stage in proceedings and indicates that the regulator believes there is a case to answer.
The move is part of a larger FERC push to crack down on alleged electricity market manipulators.
It settled manipulation charges with a JPMorgan Chase subsidiary for $410 million last week. It also has levied a $435 million fine against Barclays, which the British bank is fighting.
Read the full Reuters story here.