Hundreds of civil liberties campaigners have protested outside Belmarsh Prison at the detention of 11 foreign nationals under UK anti-terrorism laws.
Law Lords begin a review of the legality of the detention on Monday
Liberty director Shami Chakrabarti, at the protest, urged Home Secretary David Blunkett to "end this internment now".
The prisoners are held at Belmarsh and Woodhill jails, and Broadmoor Hospital.
Law Lords on Monday begin a review of the legality of the detention and whether evidence possibly obtained by torture can be used against detainees.
The men are detained under the Anti-Terrorism, Crime and Security Act 2001, introduced after the 11 September attacks.
Protesters were addressed by speakers including representatives of human rights groups and Britain's Muslim Community.
They held placards with slogans including "Belmarsh - Blair's Guantanamo".
BBC correspondent Imran Khan said protesters at the "passionate" demonstration were angry at what they see as "an illegal law" - the detention of people without trial.
They feel the law is "one step away from a dictatorship", he added.
Ms Chakrabarti told protestors she was "sick of feeling ashamed to be British, when we are supposedly living in one of the world's finest democracies".
"In a democracy we do not lock people up without trial - it's as simple as that."
She urged Mr Blunkett to "do the right thing and end this internment now".
"All decent law-abiding people realise that you can't win a war on terror by undermining the presumption of innocence and democracy," she added.
Anti-terror laws allow Mr Blunkett to detain without trial foreign nationals he suspects of terrorism, but cannot deport because it would endanger their life.
The government says the anti-terror laws are necessary for the security of the country.
Mr Blunkett insists he uses the laws sparingly and that prisoners are released when mistakes are made.
In September an Algerian known as "D" was released from Woodhill, near Milton Keynes, where he had been held since December 2001.
Mr Blunkett said the weight of evidence against him no longer justified his detention.
Of 17 foreigners originally detained under the act, "M" was freed on appeal, "G" was released to house arrest, one was detained under other powers and two
have chosen to leave the UK, as allowed by the legislation.
Sunday's protest follows a similar demonstration held in April.