"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.
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.
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.