Fewer than a fifth of people held in anti-terror inquiries in Britain since the 9/11 attacks in 2001 have been charged with terrorism-related crimes.
Some 652 of the arrests did not result in charges
The Home Office figures show that of the 1,166 people detained, just 221 were charged by the end of last year.
Officials said the arrests were made with public protection in mind - 186 people faced non-terrorism charges.
The Islamic Human Rights Commission said "heavy handed and discriminatory" policies had ruined innocent lives.
The Home Office data shows there were 1,126 arrests under the Terrorism Acts of 2000 and 2006 in the period between 11 September 2001 and the end of 2006.
There were 40 arrests under laws other than the Terrorism Act, but as part of a terrorism investigation.
Among the other information that can be gleaned from the figures are that:
The 1,166 arrests led to 40 convictions under anti-terrorism laws and 180 convictions under other legislation.
98 people are on, or are awaiting, trial.
652 of the those arrested were released without charge.
186 people were charged with non-terrorism offences including murder, firearms and explosives offences or fraud.
74 people were handed to the immigration authorities and two face extradition proceedings.
A Home Office spokeswoman said police had to make decisions over arrests based on "the circumstances presented to them", and take into account the need to conduct an effective investigation and protect the public.
The data did not specify the ethnic or religious background of those arrested but the Muslim community has contended it has been disproportionately targeted.
The IHRC called for a review of the laws.
Its chairman Massoud Shadjareh said: "It does not inspire confidence in those entrusted with our safety that less than 3.5% of those arrested under anti-terror laws are convicted in what are supposedly intelligence-led operations."
Human rights group Liberty said the data showed why attempts to extend the length of time people can be held without charge should be resisted.
Director Shami Chakrabarti said: "Inevitably, more people are arrested than charged and more are charged than convicted, yet this is all the more reason to make sure that innocent people are not locked up for longer and longer periods in pre-charge detention."