Washington: US President George W Bush on Tuesday signed into law, a controversial bill which in effect allows secret overseas CIA prisons, harsh interrogation practices and military trials as weapons against suspected terrorists.

The bill comes after a Supreme Court ruling in June which found that military tribunals set up to prosecute detainees at Guantanamo Bay violated US and international law.

“The bill I sign today helps secure this country, and it sends a clear message: This nation is patient and decent and fair, and we will never back down from the threats to our freedom,'' Bush said at a White House signing ceremony.

Bush called the Military Commissions Act "one of the most important pieces of legislation in the war on terror", said said it was a rare occasion when a president signed a law that he knew would save American lives "I have that privilege this morning," he said.

The American Civil Liberties Union in a statement called the new legislation “one of the worst civil liberties measures ever enacted in American history''.

“The president can now — with the approval of Congress — indefinitely hold people without charge, take away protections against horrific abuse and put people on trial based on hearsay evidence,'' ACLU executive director Anthony Romero said.