More than 80 independent oil and gas producers have sued units of Goldman Sachs Group Inc and BP Plc , alleging they conspired with SemGroup LP to defraud the plaintiffs of money owed for oil and gas delivered prior to the energy trader's 2008 bankruptcy.

The law firm McKool Smith announced the lawsuits by the Kansas, Oklahoma and Texas producers against Goldman's J. Aron & Co unit, BP Oil Supply Co and other defendants.

It said the lawsuits were filed in Kansas and Oklahoma state courts. The complaints were not immediately available.

Goldman and BP did not immediately respond to requests for comment.

According to the law firm, the producers are owed millions of dollars for oil and gas the defendants took from SemGroup as margin calls were driving that company toward bankruptcy.

SemGroup, based in Tulsa, filed for Chapter 11 protection from creditors in July 2008 after suffering $3.2 billion in losses on energy futures and derivatives trades that it said were designed to protect its physical oil trading business.

(Reporting by Jonathan Stempel; editing by John Wallace)