The CIA is decommissioning the secret overseas prisons where top al-Qaida suspects were subjected to interrogation methods, including simulated drowning, that Attorney General Eric Holder, allied governments, the Red Cross and numerous other experts consider torture, the agency said Thursday.

WASHINGTON — The CIA is decommissioning the secret overseas prisons where top al-Qaida suspects were subjected to interrogation methods, including simulated drowning, that Attorney General Eric Holder, allied governments, the Red Cross and numerous other experts consider torture, the agency said Thursday.

In an e-mail to agency employees outlining current interrogation and detention policies, CIA Director Leon Panetta also said agreements with the private security firms guarding the so-called black sites will be “promptly terminated,” and contractors no longer will be used to conduct interrogations.

Panetta, however, said CIA officers who were involved in interrogations using “enhanced” methods authorized by the Justice Department during the Bush administration “should not be investigated, let alone punished.”

The Justice Department is investigating the destruction of CIA interrogation videotapes, while the Senate Intelligence Committee has started an inquiry into the interrogation and detention program authorized by the Bush administration as part of its post-9/11 “war on terrorism.”

The steps announced by Panetta are consistent with a Jan. 22 executive order in which President Obama directed the CIA to halt the use of its secret overseas detention facilities and use only interrogation procedures authorized by an Army Field Manual.

Panetta said his agency’s pursuit of al-Qaida and allied groups has continued “undiminished” in “strict accord” with Obama’s order.

He said the CIA “no longer operates” detention facilities and has developed a plan to “decommission” them that includes terminating the contracts with the private security firms that guard them.

“I have directed our Agency personnel to take charge of the decommissioning process,” he wrote.

“It is estimated that our taking over site security will result in savings of up to $4 million.”

The CIA has refused to disclose the locations of its detention facilities.

They reportedly are in Afghanistan, Jordan, Poland, Romania and Thailand, and CIA officials have said they held fewer than 100 suspected terrorists.