Madoff's sons sued 

Source: ReutersAccused swindler Bernard Madoff (bottom) enters the Manhattan federal court house in New York on March 12, 2009

Two former employees of the legitimate trading side of confessed swindler Bernard Madoff's operations have sued his sons, saying they must have known their father's business was a sham.

In two separate lawsuits filed in New York State Supreme Court, former employees Reed Abend and Richard Stahl accuse Mark and Andrew Madoff of fraud for knowingly cheating them out of salaries when the company collapsed after Bernard Madoff's arrest last December.

Mark and Andrew Madoff were executives at the brokerage arm of their father's company. The nefarious activities took place in a separate investment advisory business run by Bernard Madoff and other close associates.

Neither Mark nor Andrew Madoff have been charged with any crime, but their assets have been frozen.

"In order to perpetuate their father's lawless conduct, the Madoff sons made statements to (Abend and other employees) and failed to disclose Madoff Securities' criminal actions in order to induce (Abend and others) to continue to earn legitimate profits," Abend's lawsuit said.

Both men portrayed themselves as skilled traders who earned the company large profits, "during the worst market sell-off in recent memory," according to Stahl's lawsuit.

Stahl claims he is owned more than $US1 million in compensation, while Abend claims a loss of at least $US473,940.

Lawyers for Madoff's sons could not immediately be reached for comment.

The disgraced money manager has been jailed since pleading guilty in March to a fraud that investigators say bilked clients of as much as $US65 billion over 20 years.

He could be ordered to spend the rest of his life in prison when he is sentenced June 29 at US District Court in Manhattan.