A British system under which suspected terrorists not charged with any crime were forced to live under partial house arrest was among the most repressive tools used in the West, the country's anti-terrorism watchdog said Monday.
David Anderson, a lawyer responsible for reviewing Britain's legal efforts to combat terrorism on behalf of the government, disclosed in an annual report that a total of 52 people had been held under the control order between 2005 _ when the measures were introduced _ and the end of 2011, when the system was replaced.
The system allowed authorities to impose a curfew of up to 16 hours per day, required a suspect to wear an electronic anklet, restricted their contact with others and could ban an individual from using the Internet or traveling overseas.
Anderson said that a total of 23 people also had been forced to move away from their home to a different part of Britain under the system. The tactic _ dubbed internal exile by its critics _ was intended to help disrupt suspected terrorist cells in specific cities.
He called the controversial program the "more repressive end of the spectrum of measures operated by comparable Western democracies."
Control orders were imposed after Britain's courts outlawed the jailing of suspects without trial in 2004. Those detained under the program included suspects tied to a 2006 plot to down trans-Atlantic airliners with liquid explosives, an alleged senior al-Qaida fixer, and a man who repeatedly declared his desire to carry out a suicide attack.
"The majority of control orders were imposed on the basis of the home secretary's suspicion that the subject was a hardened terrorist, actively involved in terrorist plots in the U.K. or abroad," Anderson said in his report.
However, he acknowledged that "a smaller number, particularly in the early years, were imposed chiefly on suspicion of the subject wishing to travel abroad for terrorist purposes."
Anderson said the control order program had been successful in protecting the public from a small number of suspects who authorities had been unable to prosecute _ most commonly over the government's reluctance to disclose sources of intelligence _ but that there had been "something unsettling" about the system.
Critics have long complained that control orders and other tough anti-terrorism measures alienated British Muslims, hampering law enforcement efforts to win their support and gather intelligence on extremists.
Anderson confirmed that nine British suspects who were being held under a control order when the system was axed at the end of 2011 had been placed under a new, less stringent monitoring program.
Under the new system, known as terrorism prevention and investigation measures, suspects can be required to wear an electronic tag and stay at a specific address overnight for about eight to 10 hours. They can be banned from visiting specific buildings or people, and have only a limited ability to visit websites from any home computer.
However, the new measures are limited to a maximum of two years, suspects cannot be sent to other areas of the country and a higher burden of evidence is required before they can be imposed.
Anderson acknowledged that the new system could not offer the same protections as its predecessor and raised concern that some determined terrorists would put up with restrictions for two years before seeking to resume their activities.
He said the change "was a political decision, taken on civil liberties rather than national security grounds."