The bankruptcy trustee of Refco, the failed futures brokerage, has sued investor Thomas H. Lee and his former private equity firm, alleging they ignored accounting and other problems at Refco in their rush to take the company public.

The lawsuit, filed in a federal court in New York on Wednesday, seeks more than $500m from Mr Lee and Thomas H. Lee Partners, who bought control of Refco in a 2004 leveraged buy-out and then took it public in August 2005. Refco collapsed just two months later when it announced that Phillip Bennett, the firm’s founder, had disguised a $430m debt he owed the company.