New York: Raj Rajaratnam and Danielle Chiesi, co-defendants in the biggest hedge-fund insider-trading case, asked a federal judge to allow them to be tried separately.

"The cumulative impact of evidence presented against Ms Chiesi will improperly spill over to Mr Rajaratnam, compromising Mr Rajaratnam's trial rights," his lawyers wrote in a court filing on Friday. Chiesi's lawyers filed a separate motion asking for the same relief earlier Friday.

Rajaratnam, co-founder of New York-based Galleon Group, is accused of using secret tips from hedge-fund executives including Chiesi, corporate officials and other insiders to earn millions of dollars in illegal stock trades. The allegations involve trading shares in 12 companies, including Intel Corp, International Business Machines Corp, Akamai Technologies Inc, Google Inc and Advanced Micro Devices Inc.

Rajaratnam and Chiesi are among 21 people accused since October in two overlapping insider-trading cases. Ten people have pleaded guilty so far in the criminal cases. Rajaratnam and Chiesi are scheduled to be tried on October 25.

Janice Oh, a Justice Department spokeswoman, declined to comment on Rajaratnam's and Chiesi's requests.

Rajaratnam also asked the judge to compel the government to produce documents relating to former Intel executive Roomy Khan.