Milberg Weiss is one of the best-known law firms that bring class actions on behalf of shareholders and customers against large companies. The firm boasts that it has recovered more than $45 billion (£22.3 billion) on behalf of clients in cases connected with financial fraud.

David Bershad, a 67-year-old former managing partner at the law firm, yesterday agreed to plead guilty to conspiracy to obstruct justice and make false statements under oath. Those charges could attract a sentence of up to five years in prison. Mr Bershad has agreed to return $7.75 million, pay a $250,000 fine and cooperate with the US Attorney’s office in Los Angeles.

For the past seven years, federal prosecutors have been investigating whether Milberg Weiss, the firm, Mr Bershad and his former partner Steven Schulman took part in a scheme to pay millions of dollars in illegal kickbacks to shareholders so that they would serve as lead plaintiffs in class action fraud cases.

The prosecutors were trying to ascertain whether, once a case was settled, some of the legal fees due to the firm were paid to the lead plaintiffs. Such payments are illegal because lead plaintiffs have to represent other members of the class action and have to declare that their interests are in line with the others’.

Mr Bershad was indicted last year by a Los Angeles grand jury along with Mr Schulman for making such payments in cases where the firm was paid $216 million. Milberg Weiss and Mr Schulman, who has since retired, pleaded not guilty. The trial is to due to start in January.

In a statement, Milberg Weiss & Bershad said: “We understand David Bershad will plead guilty today to conspiracy to obstruct justice. Mr Bershad had been on a leave of absence since May 2006 and his relationship with Milberg Weiss LLP has been terminated. We remain confident that his actions will have no effect on the firm’s commitment to its clients and its ongoing work to protect public shareholders and consumers.”

Federal investigators finally got lucky in the long-running inquiry in May last year. Los Angeles prosecutors secured a guilty plea from Howard Vogel, who admitted that he and his family had received $2.5 million in illegal payments from the law firm in return for becoming lead plaintiffs in a number of class actions. Mr Vogel named four partners at Milberg Weiss and also agreed to cooperate with the investigation.

Mr Bershad had responsibility for overseeing the finances and accounting processes of Milberg Weiss, according to court papers.