UNITED NATIONS - UN human rights chiefs and experts launched a new offensive on the US conduct of its "war on terror" and conflicts in Iraq and Afghanistan.
The leaking of 400,000 documents on the Iraq war and war crimes charges against a former Al-Qaeda child soldier at the Guantanamo prison camp has opened the door to new criticism despite President Barack Obama's efforts to improve the US image.
UN human rights chief Navi Pillay on Tuesday urged Iraq and the United States to investigate allegations of torture and unlawful killings in the Iraq conflict revealed in documents released by Wikileaks.
A UN investigator on torture called for an investigation into all US practices since the September 11, 2001 attacks. Another UN expert called the US military hearing against a young Al-Qaeda operative at Guantanamo "a disgrace."
A US official expressed surprise at the new criticism but, speaking on condition of anonymity, said "even the UN knows that the situation has changed since the president (Obama) came to office" in January 2009.
Pillay, based in Geneva, said the United States and Iraq should investigate all allegations in the Wikileak documents and "bring to justice those responsible for unlawful killings, summary executions, torture and other serious human rights abuses."
She said documents released by the whistleblowing website added to her concerns that serious human rights breaches had occurred in Iraq, including "summary executions of a large number of civilians and torture and ill-treatment of detainees."
The files indicate that despite knowing about "widespread use of torture and ill-treatment of detainees by Iraqi forces" the US military still handed over thousands of detainees to Iraq between early 2009 and July 2010, Pillay said.
The US case was also taken up by UN special rapporteurs on rights who are giving their annual reports to the UN General Assembly.
Manfred Novak, UN special rapporteur on torture, said he was denied admission to detention centers in Iraq by American officials.
He acknowledged a change in US actions since Obama came to power but added that there should be a "full investigation" into practices by the US military, intelligence and private companies since 2001.
Novak called the Guantanamo camp "illegal" while another UN expert attacked hearings at the camp against former Al-Qaeda youth soldier and Canadian national Omar Khadr as "a disgrace and a shame for the United States."
Martin Scheinin, special rapporteur on counter-terrorism and human rights, said none of the charges made against Khadr fit the international notion of a war crime.
Khadr pleaded guilty on Monday to five war crimes charges before a US military commission at the camp in Cuba.
Khadr, who was 15 when detained in eastern Afghanistan in 2002, pleaded guilty to hurling a grenade that killed a US soldier and four other charges. As part of a plea deal he could reportedly be returned to Canadian custody after spending another year in US detention.
"None of the crimes for which Omar Khadr pleaded guilty are war crimes. Not a single one," said Scheinin, a professor of international law at the European University Institute in Florence, Italy.
He highlighted how the action against Khadr was "retroactive" because the crimes which he is accused of had been "codified" in the special law which set up the Guantanamo commissions. Khadr should be dealt with before an ordinary court, Scheinin told AFP.
UN officials have acknowledged efforts by Obama to close down Guantanamo which have been frustrated by the US Congress and failed moves to find a US state for an alternative prison.