The UK's new anti-terrorism laws are creating a "Guantanamo Bay in our own back yard", says Amnesty International.
Amnesty held a Guantanamo protest during President Bush's visit
Foreign nationals are being denied the presumption of innocence until proven guilty, the human rights group says.
It says the UK has created a different justice system for foreigners, who are held indefinitely without charge, and is not meeting international standards.
But the Home Office says the laws are about national security and ensuring the safety of the public.
Amnesty's report, Justice Perverted, looks at the use of the Anti-terrorism, Crime and Security Act 2001.
The report focuses on 14 suspected terrorists who have been detained at high-security prisons under the Act.
Amnesty's UK director, Kate Allen, told the BBC's Today programme: "They have been locked up on the basis of secret evidence which they haven't been able to see.
"There's no prospect at all of them having a trial, so this is very much like Guantanamo Bay," she said, referring to the US camp in Cuba being used to hold terror suspects.
Six of the suspects in the UK will have been held for two years on 19 December.
"We are saying these people should be charged or they should be released. We are not doing anything to win this war on terrorism by trampling on human rights at home."
She added that it was the duty of a democracy to use measures it could stand by and claimed repressive regimes around the world would use the UK's example to justify their own measures.
Right of appeal
But a Home Office spokesman said the Court of Appeal had ruled detentions did comply with the European Court of Human Rights.
And suspects had a statutory right of appeal to the Special Immigration Appeals Commission (SIAC).
He added: "All the detainees have the right to leave [the country] at any time, two of whom have chosen to do so."
The SIAC allows suspects the right of appeal, but uses special advocates appointed by the Attorney General and vetted by MI5 and MI6 to see the evidence on their behalf.
Amnesty has also raised concerns the SIAC may have used evidence gained by torture from suspects held in Afghanistan and Cuba.
The Home Office says that while it does not condone torture, it has to "look carefully at any intelligence gained by other countries" suggesting a threat to UK security.