Amid calls for torture prosecutions, former Bush administration officials yesterday slammed President Barack Obama's release of terror interrogation memos, warning the move would fuel "timidity and fear" among US spies.

Unhappy with Mr Obama's promise not to prosecute CIA officials, human rights groups have demanded criminal investigations of officials who approved or used the interrogation techniques chillingly detailed in the Justice Department memos.

But in an editorial in The Wall Street Journal, former CIA director Michael Hayden and former attorney general Michael Mukasey charged that disclosure of the memos "was unnecessary as a legal matter, and is unsound as a matter of policy."

"Its effect will be to invite the kind of institutional timidity and fear of recrimination that weakened intelligence gathering in the past, and that we came sorely to regret on September 11, 2001."

White House senior adviser David Axelrod countered that Mr Obama's decision to release the memos written by top legal officials in George W. Bush's administration was "a weighty decision."

Mr Obama "thought very long and hard about it, consulted widely, because there were two principles at stake," Mr Axelrod told the Politico news website.

"One is the sanctity of covert operations and keeping faith with the people who do them, and the impact on national security, on the one hand. And the other was the law and his belief in transparency."

Mr Obama consulted officials from the Justice Department, the CIA, the Homeland Security Department and the director of national intelligence, he said.

In releasing the four partially blacked-out memos, Mr Obama said last Thursday that the interrogation tactics, which have been widely denounced as torture, "undermine our moral authority and do not make us safer."

But he also pledged not to prosecute operatives who carried out the interrogations because they acted with the approval of the Justice Department and were defending their country.

The American Civil Liberties Union, which brought the lawsuit that forced the release of the memos, said Mr Obama's position against prosecutions was "untenable."

"There can be no more excuses for putting off criminal investigations of officials who authorised torture, lawyers who justified it and interrogators who broke the law," said Anthony Romero, the ACLU's executive director.

The Centre for Constitutional Rights noted that it has tried to bring criminal cases in Europe against former defence secretary Robert Gates, former CIA director George Tenet, and former Attorney General Alberto Gonzalez.