A legal adviser to the US has conceded that her country has “crossed the line” since the September 11 attacks, assuring that Washington takes responsibility for its deeds.

“In the wake of the 9/11 attacks, we [the US] regrettably did not always live up to our own values, including those reflected in the [UN] Convention [Against Torture],” Mary McLeod, US acting legal adviser from the Department of State, told the Committee Against Torture, a UN body that aims to prevent torture and inhuman treatment around the world.

“As President Obama has acknowledged, we crossed the line and we take responsibility for that,” she said.

Ten independent experts from the UN anti-torture body gathered to ‘grill’ some 30 senior US officials, including McLeod, in Geneva, Switzerland, for the first time since 2006. The committee discussed issues dealing with torture at CIA ‘black sites’, Guantanamo Bay prison in Cuba and detention of illegal immigrants.

"There's sort of a common denominator about all of our questions, and that is implementation of transparency and accountability," Jens Modvig, one of the panel's investigators, told AFP.

A day before the panel, the committee gathered evidence from anti-torture activists, death penalty experts, Murat Kurnaz, a former Guantanamo detainee, and the parents of Michael Brown, a black teenage boy from Ferguson, Missouri, who was shot in August by a white police officer.

Kurnaz, who was held at Guantanamo Bay for five years before being released without charges, said that148 prisoners still remain at the notorious prison.

"I cannot believe that Guantanamo is still open… Just being at Guantanamo is torture," he told AFP, adding that many of the remaining detainees "are as innocent as I am.”

The parents of Michael Brown, met the members of the UN anti-torture body behind closed doors on Tuesday.

READ MORE: Ferguson grand jury decision: Gun sales spike, Missouri Gov vows strong response to protests

"We came here to the UN to get justice for our son," Michael Brown Sr. told reporters.

During the Committee panel McLeod claimed that “the US is proud of its record as a leader in respecting, promoting, and defending human rights and the rule of law, both at home and around the world.”

According to McLeod, Washington follows the Executive Order on Lawful Interrogations, which states that “any individual detained in armed conflict by the United States or within a facility owned, operated, or controlled by the United States, in all circumstances, must be treated humanely and must not be tortured or subjected to cruel, inhuman, or degrading treatment or punishment.”

But Laura Pitter, representing Human Rights Watch said HRW is still concerned that the US was still limiting the applicability of Convention against Torture.

"It should apply wherever the US has effective control, not merely where it has governmental authority," she told AFP, adding that the move "does little to allay concerns that the US is looking for wiggle room in terms of how it applies its treaty obligations."

Bush admin accused of ‘enhanced interrogation techniques’

Several delegates of the Committee said that some abuses in torture took place during the ‘War on Terror’ (WOT), also known as the ‘Global War on Terrorism’ (GWOT). First used by US President George W. Bush, the term applied to the international military campaign launched after the September 11, 2001, terrorist attacks.

According to the UN body, Bush authorized the use of "enhanced interrogation techniques" like waterboarding.

"We have cleaned up those policies," a US official, told APFP on condition of anonymity, adding that most of the criticism since 2009 centered on ensuring accountability for past abuses.

In the meantime, according to Jamil Dakwar from American Civil Liberties Union said that “six years into the Obama administration, [it] has not provided full accountability for torture and abuse in US custody, especially in CIA detention,"

“The legacy of this administration could foster immunity and impunity for torture and abuse, both at home and abroad," he said.