Amnesty International has called on foreign governments not to co-operate with US military trials of detainees at Guantanamo Bay.
In a report, the human rights group said other countries should refuse to provide evidence for prosecutions. The US authorities should also abandon its system of military commissions and try suspects in civil courts on the US mainland, the report said. The military trials are due to resume at Guantanamo next week.
"Military commissions are a complete travesty of justice - no more, no less," Amnesty International UK director, Kate Allen, said. "These trials threaten to cut corners in pursuit of a few convictions and add to the injustice that the Guantanamo detention facility has come to symbolise," Amnesty's Americas Program Director Susan Lee added.
The comments come as Amnesty launched a report - Justice delayed and justice denied? - which raises concerns about the fairness of such trials and the admissibility of evidence obtained under torture. The report also highlights the limited right of appeal and the risk of so-called "enemy combatants" being returned to indefinite custody even if they are acquitted.
The US is preparing to restart the tribunals on 27 March with the scheduled arraignment of Australian detainee David Hicks, who is charged with providing material support for terrorism by fighting for al-Qaeda in Afghanistan. Mr Hicks, 31, is the only person charged so far under a new system of war crimes trials authorised by the US Congress.
The US has declared its intention to try 60 to 80 of the 385 foreign captives held at Guantanamo, including 14 "high-value" prisoners sent there from secret CIA prisons last year.