Britain has arrested more than 1,400 people under anti-terrorism laws since September 11, 2001, the government said on today, but only a third of those were charged and less than one led to a conviction.
Releasing the first complete statistics on the issue, covering the period from the attacks on the United States to March 31, 2008, the Home Office said there had been 1,471 arrests under the Terrorism Act.
Of those, 521 (35 per cent) resulted in charges being brought, of whom 102 (7 per cent of the arrests) were ultimately convicted under terrorism legislation. A further 94 were convicted under non-terrorism legislation.
The statistics do not, however, include those who are charged and awaiting trial, or those who have been convicted of a terrorism-related crime since March 2008.
Paul Wiles, chief scientific adviser at the Home Office, said the proportion of those arrested who were later charged was similar to the rate for other criminal offences.
But broadly the statistics appeared to show a relatively low arrest-to-conviction rate, with British juries recently failing to convict defendants in some high-profile terrorism trials.
Wiles offered no interpretation of the statistics, saying they were being produced purely as part of a data series that will see the figures updated every quarter in the future.
"The main offences for which suspects were charged under terrorism legislation were possession of an article for terrorist purposes, membership of a proscribed organisation, and fundraising, all offences under the Terrorism Act," he said.
The figures showed that 117 people are currently serving prison sentences in England and Wales for terrorism or terrorism-related convictions. Of those, 62 per cent were UK nationals and 91 per cent classified themselves as Muslims.