Demonstrators gathered outside Downing Street on Thursday to protest about the detention without trial of terror suspects held under emergency laws.
Many of the detainees are held at Belmarsh Prison
It followed news the UK is negotiating with several North African countries to allow the deportation of detainees held under anti-terror laws.
Twelve suspects are being held at Belmarsh prison, south east London, and at Woodhill jail, Milton Keynes.
According to organisers, about 300 people took part in the protest.
Civil rights groups want assurances the men will not be tortured at home.
Under human rights law, the suspects cannot be deported if there is a risk of them being tortured or sentenced to death in their homelands.
New agreements would seek guarantees that any suspects who were deported would not face oppression.
Shami Chakrabarti, director of Liberty, said: "It is vital that as many people as possible show their concern on the issue of detention without trial.
"We urgently need a better response from the home secretary which includes the repeal of this odious law and the criminal charge or release of these men."
The Anti-Terrorism, Crime and Security Act 2001 allows Home Secretary Charles Clarke to detain without trial foreign nationals he suspects of terrorism.
But there has been widespread condemnation by human rights activists, who say the practice is akin to mental torture.
Government lawyers have argued before the committee that its policy of holding foreign nationals suspected of terrorist activities is justified because there is an emergency threatening the life of the nation.