Washington ? The chairman of the Senate Intelligence Committee is questioning whether the CIA’s secret prison program – which he fears has become a black eye to the United States – should continue.

The review led by Sen. Jay Rockefeller, D-W.Va., comes as the Bush administration deliberates an executive order, called for by Congress, that will establish new guidelines for the CIA’s system for detaining and interrogating suspected terrorists. It is the agency’s most publicly controversial intelligence collection program.

Rockefeller says there is no doubt that intelligence from detainees has been valuable. Yet he says he wonders whether the CIA needed to create a system outside of long-standing FBI and military interrogation programs.

President Bush said he emptied the CIA’s secret prisons in September and sent its last 14 high-value detainees to the U.S. prison at Guantanamo Bay, Cuba. But he left open the possibility that the program could be used again.

As chairman, Rockefeller has promised to conduct more vigorous oversight of the spy agencies than did his Republican predecessor. He is asking whether having a separate CIA detention and interrogation system is necessary and worth the toll on the U.S. image abroad.

Human rights groups have argued that the CIA’s detention and interrogation techniques amount to torture. The International Committee of the Red Cross is the only independent watchdog to interview the 14 detainees held by the CIA.

In a confidential report, the Red Cross said the 14 prisoners described highly abusive interrogation methods, especially when techniques such as sleep deprivation and forced standing were used in combination. None of the detainees’ accounts has been verified.

U.S. officials have said the CIA program is for the most dangerous detainees, and the CIA says its officers do not torture.

As part of the Senate committee’s work, members have visited the U.S. detention facilities at Guantanamo Bay; such fact-finding trips are expected to continue.

One committee aide said that for some time, the administration would not brief the full House and Senate intelligence committees on the program’s most sensitive aspects and limited those briefings to just a few members. More recently, the administration has begun giving more complete information to the full Senate committee. The aide spoke on condition of anonymity, citing office policy.

The House committee, led by Rep. Silvestre Reyes, D-Texas, has had private briefings with CIA Director Michael Hayden and expects more. Reyes wants to see the Justice Department’s legal memos justifying the CIA program.

“The chairman is not going to approve any intelligence activity until he has an opportunity to review the legal basis for it,” said a House committee aide who was authorized to speak to reporters only if not identified.

Bush did not acknowledge the CIA’s secret detention program until September, when he announced that the agency had just moved al-Qaida operational planner Khalid Sheikh Mohammed and 13 other suspected terrorists to Guantanamo Bay.