"There were 412 arrests for terrorism-related offenses in the year ending 31 December 2017, an increase of 58% compared with the 261 arrests in the previous year. This was the highest number of arrests in a year since the data collection began," the report said.
So far, the number of detentions on suspicion of terrorist activities has never exceeded 300 per year.
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Of the 412 arrests for terrorism-related offenses in 2017, "135 (33%) resulted in a charge, of which 110 (81%) were charged with terrorism-related offenses," while 228 (55 percent) were released without charge, according to the report.
A total of 33 people were released on bail, 13 faced alternative action and three cases were pending at the time of data provision.
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The high increase in the number of arrests for terrorism-related offenses is a result of the fact that in 2017 the United Kingdom faced five terrorist attacks.