WASHINGTON - June 9, 2008 - U.S. interrogators of "war on terror" detainees were instructed to destroy handwritten notes that might have exposed harsh or even illegal questioning methods at Guantanamo Bay, Cuba, a lawyer for one of the prisoners said Sunday.

Navy Lieutenant Commander Bill Kuebler said in a statement sent to reporters he considers the notes crucial to the defense of his client, Canadian Omar Khadr, during his upcoming murder trial by a special military tribunal at the U.S. naval base.

Kuebler said the instructions were handed down to interrogators from the U.S. Department of Defense as part of a standard operating procedure or "SOP" directive that he obtained from prosecutors last week.

If they were carried out, U.S. interrogators may have "routinely destroyed evidence" that might have been used to defend the Khadr and other detainees, Kuebler charged.

"If handwritten notes were destroyed in accordance with the SOP, the government intentionally deprived Omar's lawyers of key evidence with which to challenge the reliability" of alleged confessions made to military interrogators, Kuebler said.