The human rights group said on Monday that Algeria's intelligence agency, the Department of Information and Security, or DRS, is using the war on terror as an excuse to perpetuate torture and ill-treatment.
The rights group issued its 44-page report before Abdelaziz Bouteflika, the president, visits London on Tuesday.
"Recent measures taken by the Algerian authorities with the stated intention of consolidating 'national reconciliation' have failed to address this grim legacy," it said.
The most common means of abuse, it said, include beatings, electric shocks, and "chiffon" - the forced drinking of dirty water, urine or chemicals through a cloth stuffed into a detainee's mouth.
The group called on the Tony Blair, the British prime minister, to urge Bouteflika during their meeting to investigate allegations of torture and abuse.
Bouteflika "must also ensure that DRS officers no longer arrest or detain suspects and that any responsible for torture or mistreatment of detainees are promptly brought to justice," said Malcolm Smart, director of Amnesty International's Middle East and North Africa Programme.
Blair and Bouteflika are expected to sign agreements on the deportation from Britain of convicted criminals and failed asylum seekers.
But a British foreign ministry spokesman said on Monday that negotiations continue over a deal in which Britain would return "terror suspects" to Algeria in return for diplomatic assurances that they will not be tortured or abused.
About 150,000 people - Islamists, civilians, military - died in an insurgency triggered in 1992 by the Algerian army's decision to cancel legislative elections that an Islamist party was poised to win.
Algeria: Persistent torture by the military security in secret locations - Amnesty International