By David Ingram

WASHINGTON (Reuters) - A federal judge twice considered by President Barack Obama for the Supreme Court has rebuked theadministration over the secrecy surrounding aerial drone strikes abroad, adding to pressure Obama already faces from fellow Democrats.

A ruling on Friday from Judge Merrick Garland in Washington capped a week of mounting calls for the release of more information and follows a drawn-out confirmation process for the new director of the Central Intelligence agency, John Brennan.

The Obama administration defends the attacks as essential to the fight against al Qaeda and other militants in countries such as Pakistan and Yemen. The strikes have at times killed civilians who were not targets, ignited local anger and frayed diplomatic ties.

A Democratic senator confronted Obama about the drone program at a closed-door meeting on Tuesday, the Politico newspaper reported, and on Wednesday a lawyer who led Obama's 2008 presidential transition, John Podesta, wrote an opinion piece accusing the administration of wrongly withholding drone-related legal opinions.

Garland, writing for himself and two other judges on the Court of Appeals for the District of Columbia Circuit, criticized the Central Intelligence Agency for refusing in a lawsuit even to acknowledge the existence of its drone program. He called the CIA's legal reasoning indefensible and a fiction.

"'There comes a point where... courts should not be ignorant as judges of what (they) know as men' and women," Garland wrote, quoting a 1949 Supreme Court opinion.

"We are at that point with respect to the question of whether the CIA has any documents regarding the subject of drone strikes," he wrote.

The ruling effectively revives a lawsuit in which the American Civil Liberties Union is asking for records from the CIA. Obama administration lawyers have opposed the suit.

TRANSPARENCY DEBATE

In response to the ruling, a National Security Council spokeswoman said the administration had been more transparent than any of its predecessors on the conduct of sensitive counterterrorism operations but would not discuss details of specific operations.

Caitlin Hayden, the spokeswoman, said in a statement: "We will continue to disclose as much as we can - as soon as we can - regarding the framework, the standards, and the process through which we approve such operations."

Justice Department spokeswoman Nanda Chitre said the department was reviewing the decision, while CIA spokesman Todd Ebitz said: "The CIA does not, as a rule, comment on matters before the courts."

Attorney General Eric Holder said in congressional testimony on March 6 that Obama would soon reveal more about the legal rationale for drone strikes.

"We have talked about a need for greater transparency," said Holder, the chief U.S. law enforcement official.

Democrats outside the administration have shown growing impatience with the secrecy. West Virginia Senator Jay Rockefeller, a former Senate Intelligence Committee chairman, urged Obama to be more open during the president's meeting with Senate Democrats on Tuesday, Politico reported.

Podesta, a Democratic insider who oversaw Obama's 2008 transition, wrote in The Washington Post on Wednesday that Obama "is ignoring the system of checks and balances that has governed our country from its earliest days."

Last week, two Democratic senators voiced similar ideas in voting against confirming John Brennan as Obama's CIA director. Brennan was confirmed to the post on March 7, but the confirmation process was delayed for weeks by concerns about the administration's use of drones.

HIGH COURT CANDIDATE

Garland, 60, was a high-level Justice Department official when President Bill Clinton appointed him a judge.

He was on Obama's list of candidates for the Supreme Court when vacancies arose in 2009 and 2010. Obama chose others, but Garland remains a frequently cited judge on the influential appeals court in Washington.

In its efforts to quash the ACLU's records suit, the CIA said it could neither confirm nor deny whether it had drone records because of security concerns.

The ACLU, which sued under the 1966 Freedom of Information Act, countered that government officials had already acknowledged the drone program in public statements from 2009 to 2012.

The question became whether the statements by Obama, former CIA Director Leon Panetta and former counterterrorism adviser Brennan amounted to an official acknowledgment.

Garland ruled that they did, writing, "The president of the United States has himself publicly acknowledged that the United States uses drone strikes against al Qaeda."

However, if the case follows the pattern of similar suits, the ACLU is likely a long way from getting any records. Its suit now heads back to a trial court, where the CIA could invoke other defenses against the records request.

Jameel Jaffer, deputy legal director of the ACLU, said the ruling would make it more difficult for the government to deflect questions about drones.

"The public surely has a right to know who the government is killing, and why, and in which countries, and on whose orders," Jaffer said in a statement.

(Additional reporting by Mark Felsenthal and Tabassum Zakaria; Editing by Howard Goller and David Brunnstrom)