Wednesday's ruling by District Judge Vaughn R. Walker in Northern California District Court reaffirmed an earlier decision that the warrantless wiretaps conducted on an Oregon-based Islamic non-profit organization were illegal, CNN reported.

The United States has designated the Oregon-based al-Haramain Islamic Foundation as a terrorist organization. The group, which has sued the government over alleged warrantless wiretapping, is demanding classified information about the programme launched by President George W. Bush's administration.

US officials have refused to tell the charity's lawyers whether the group was subjected to presidentially authorised, warrantless, foreign intelligence surveillance in 2004 and, if so, what information was obtained, CNN said.

The US stance originated under the Bush administration in what is called the "state secrets" defence, which allows courts to block lawsuits against the government on grounds that the litigation could harm national security.  Under Bush, the government refused to turn over any classified evidence.

Obama's Attorney General Eric Holder has so far maintained the state secrets defence in the al-Haramain case, but indicated a willingness to consider sharing information with judges in certain cases.

"An additional review was conducted at the highest levels of the Department of Justice to determine whether continued invocation of the privilege was warranted," the government told the court last May.

"Based on that review, it is the government's position that disclosure of classified information ... would create intolerable risks to national security."

Walker's ruling Wednesday rejected that defence, saying that for the purposes of the case, the court decided there was no warrant for the wiretaps because the government refused to confirm one existed, CNN said.

"Defendants have foregone multiple opportunities to show that a warrant existed, including specifically rejecting the method created by Congress for this very purpose," the ruling said.

In 2007 the 9th US Circuit Court of Appeals overturned a ruling by Walker in the same case in which he had rejected the government's state secrets privilege. The ruling, however, left unanswered whether applicable laws could pre-empt the state secrets privilege, so al-Haramain went back to court to continue the fight on that issue.