NEW YORK (Reuters) – Federal investigators are examining the possibility of improper leaks regarding the government's insider trading case against Raj Rajaratnam, according to materials released yesterday by representatives for the Galleon Group founder.

The US Department of Justice's Office of Professional Responsibility has opened an inquiry into allegations of misconduct by individuals in the US Attorney's office and the FBI, a May 11 letter to Rajaratnam's lawyer John Dowd shows.

Meanwhile, David Kotz, the inspector general for the US Securities and Exchange Commission, phoned Dowd this month and advised that he would look into the matter, the defence team said.

The Justice Department, the SEC and Kotz declined to comment. The Wall Street Journal, which Rajaratnam's team said published several articles with improperly leaked material, did not immediately reply to a request for comment.

Dowd had written on April 20 to US officials including Kotz and Attorney General Eric Holder, saying that leaks such as the contents of potentially unconstitutional wiretaps and the identities of unindicted alleged co-conspirators have compromised Rajaratnam's right to a fair trial.

Since Rajaratnam's arrest on October 16, 2009, more than 3,000 articles have appeared in print regarding the case, including 419 in the New York area, Dowd wrote.

"The result is precisely the kind of 'trial by newspaper' that the Supreme Court has held unconstitutional," he wrote. Dowd, a partner at Akin Gump Strauss Hauer & Feld LLP, said the probe has "destroyed" Galleon and his client's reputation.

A former billionaire, Rajaratnam is the central figure in a sprawling hedge fund insider trading case in which 21 traders, executives and lawyers have been charged in connection with the alleged illegal trading of dozens of stocks.

Eleven have pleaded guilty to criminal charges. The first to be sentenced, Mark Kurland of New Castle Funds LLC, was sentenced on Friday to 27 months in prison.

Rajaratnam has pleaded not guilty to criminal charges, and also faces civil charges by the SEC.

The cases are US v. Rajaratnam, US District Court, Southern District of New York, No. 09-01184, and SEC v. Galleon Management LP in the same court, No. 09-08811.