The U.S. told a U.N. watchdog panel Monday that it forbids all employees from torturing detainees and has improved measures to prevent any mistreatment.

In its first appearance in six years before the U.N. Committee Against Torture, a U.S. delegation said that laws, training and monitoring have improved in the several years since most of the "regrettable incidents or allegations" of detainee mistreatment occurred.

Deputy Assistant Secretary of Defense Charles Stimson said the U.S. had failed in its duty to protect detainees in Iraq.

"We feel terrible about what happened to these Iraqi detainees," Stimson said. "We didn't do that (protect them) and that was wrong."

The delegation headed by State Department legal adviser John B. Bellinger III was answering the panel's questions on topics ranging from Washington's interpretation of the absolute global ban on torture to its interrogation methods in prisons such as Abu Ghraib in Iraq, and Guantanamo Bay, Cuba.

Bellinger said that most of the "regrettable incidents or allegations" of detainee mistreatment took place several years ago.

"I say this not to minimize their significance, but to emphasize that, without question, our record has improved," Bellinger said. "U.S. officials from all government agencies are prohibited from engaging in torture at all times and in all places."

Stimson said that waterboarding, an intensely criticized technique in which prisoners are strapped to a plank and dunked in water, is not permitted in the current Army Field Manual and is "specifically prohibited" in a revised version, which has not yet been published.

However, the waterboarding accusations have been levied against the CIA, and U.S. officials declined to discuss intelligence rules.

There have been about 800 investigations into allegations of mistreatment in Afghanistan and Iraq, Stimson said. The Defense Department took action against more than 250 service personnel; there have been 103 courts-martial and 89 service members were convicted, of whom 19 received sentences of one year or more.

Stimson noted that these numbers contrasted with those calculated by Human Rights Watch, which said there had been only 54 convictions and 10 service members sentenced to a year or more in prison.

In the first session of the review last week, members of the U.N. committee told the U.S. that it had to set a better example of combating torture and could not hide behind secrecy in the war on terror in refusing to discuss violations of the global ban on prisoner abuse.

The delegation told the committee, which serves as the U.N. watchdog for a 22-year-old treaty forbidding that abuse, that mistakes had occurred in the U.S. treatment of detainees in the war against terror, and that 29 detainees in U.S. facilities in Iraq and Afghanistan had died of what appeared to be abuse or other violations of U.S. law.

Jennifer Daskal of Human Rights Watch said the presence of a large U.S. delegation indicated that the Bush administration was taking the hearing seriously, but she was still disappointed with the responses to questions.

Jamil Dakwar, staff attorney of the American Civil Liberties Union, said the government needed to go further and take "vigorous and sincere measures."

The U.S. is taking its turn as one of the 141 signatories to the Convention Against Torture in submitting to a periodic review by the 10 independent members of the committee.

Intelligence matters such as alleged secret CIA prisons and flights transferring suspects for possible torture in other countries were key items on a list of questions submitted to the U.S. government by the committee in advance.

Criticism by the U.N. panel brings no penalties beyond international scrutiny. The committee is expected to issue conclusions at the end of its session on May 19.