The increase was reflected in both the domestic and foreign terrorism categories, with domestic-related arrests rising from 10 to 52.
The numbers includes a series of arrests that were made following the Manchester and London attacks.
The figure jumped by more than 150 to 379 in the year to June, the highest since records began in 2001.
MORE than one alleged terrorist is being arrested every day as the number of suspects has soared to a record high, it emerged today.
This 379 arrest figure is 68% higher than the 226 people who were arrested for the same period the year before.
One arrest was related to the Finsbury Park attack in north London in June.
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Domestic terrorism refers to activity where there are no links to either Northern Ireland-related or global terrorism.
The figures released today show the tireless efforts of the police, Security Service and Crown Prosecution Service during what was an unprecedented period of terrorist activity in the United Kingdom'.
The number of people arrested was not made available in Wednesday's release, nor would the Home Office provide it when asked.
The new figures show a 60% jump in arrests linked to global terrorism, from 184 to 294.
Of the 379 arrests in the 12 months to the middle of this year, 123 resulted in a charge, including 105 where suspects were charged with terror-related offences. Meanwhile, 189 were released without charge. Two cases were pending at the time the statistics were compiled.
Police and MI5 are running 500 investigations involving 3,000 individuals at any one time, while there are also 20,000 former "subjects of interest" whose risk must be kept under review.