UNITED NATIONS - The UN human rights chief expressed concern Wednesday at recent US legislative and judicial actions that she said leave hundreds of detainees without any way to challenge their indefinite imprisonment.

A detainee is escorted by military guards inside Camp Delta's Maximum Security area on the US Naval base at Guantanamo Bay, Cuba in 2006. [AFP]

Louise Arbour referred to the Military Commissions Act approved by Congress last year and last month's federal appeals court ruling that Guantanamo Bay detainees cannot use the US court system to challenge their detention. The case is likely to go to the Supreme Court.

Arbour was critical of the ruling, calling on the judicial system to "rise to its long-standing reputation as a guardian of fundamental human rights and civil liberties and provide the protection to all that are under the authority, control, and therefore in my view jurisdiction of the United States."

Twice before, the Supreme Court issued ruling giving Guantanamo detainees full access to courts. But last June, the justices suggested President Bush could ask Congress for more anti-terrorism authority, prompting passage of the commissions act that in part stripped federal court review.

The act grants suspects at Guantanamo Bay the right to confront the evidence against them and have a lawyer present at specially created "military commissions." But it does not require that any of them be granted legal counsel and specifically bars detainees from filing habeas corpus petitions challenging their detentions in federal courts.

"I am very concerned that we continue to see detention without trial and with, in my opinion, insufficient judicial supervision," Arbour told a news conference after meeting with Secretary-General Ban Ki-moon.

"I thought there had been progress in that direction. There's been a legislative setback now recently in my view, a judicial decision," she said. These people have "no credible mechanism to ascertain the validity of these ... suspicious or allegations."