Energy giant BP is set to appeal against a decision by a US judge that it had manipulated gas market prices in 2008, the company said Friday.

The ruling came from the Federal Energy Regulatory Commission (FERC) Thursday, and London-based BP said it "strongly" disagreed with the decision.

"As BP demonstrated at the hearing, the FERC enforcement staff's allegations are entirely without merit," Geoff Morrell, BP's vice president for US communications and external affairs, said in a statement.

"The evidence overwhelmingly demonstrated that BP's natural gas traders did not engage in any market manipulation and FERC has no jurisdiction over the trading at issue in any event."

BP could face fines of tens of millions of dollars in the case.

Its Southeast Gulf Texas team was accused of manipulating gas prices to keep them low and strengthen their financial position in derivatives.

This allegedly took place in the two months following Hurricane Ike in September 2008, which caused significant damage in the South.

In July, BP said it would pay $18.7 billion to compensate the US government and five states for damages stemming from the 2010 Gulf of Mexico oil spill.