The U.S. Supreme Court on Monday rejected an appeal by two financial firms who sued the Mayer Brown law firm for allegedly drafting false statements on behalf of the now defunct commodities broker Refco Inc.

The court's refusal to hear the securities-fraud case comes a week after it ruled 5-4 that plaintiffs in such cases can't sue parties who draft false statements that are made by someone else. Last week's ruling barred an investor lawsuit against Janus Capital Group Inc. (JNS).

Pacific Investment Management Co., or Pimco, and another firm were seeking to revive their securities-fraud claims against Mayer Brown and one of its former partners, Joseph P. Collins, who served as outside counsel for Refco, which collapsed into bankruptcy less than two months after its initial public offering in 2005.

Refco had been a leading provider of brokerage and clearing services for international commodities, derivatives and futures markets.

Pimco, a subsidiary of Allianz SE, and RH Capital Associates alleged Mayer Brown prepared false and misleading financial documents for Refco that hid hundreds of millions of dollars in company debt.

The New York-based 2nd U.S. Circuit Court of Appeals ruled last year that Mayer Brown couldn't be held liable for the statements because they were made by Refco, not the law firm.

The Supreme Court let that ruling stand without comment.

Collins was convicted on fraud charges in 2009 and sentenced to seven years in prison. Former Refco Chief Executive Phillip R. Bennett was sentenced to 16 years in prison in 2008 after pleading guilty to a 20-count indictment.

The case is RH Capital Associates v. Mayer Brown LLP, 10-535.

-By Brent Kendall, Dow Jones Newswires; 202-862-9222; brent.kendall@dowjones.com