While more than three quarters of the arrests were related to global terrorism, there was a sharp rise in the number of arrests for domestic terrorism (from 10 to 52).
The British Home Office said that the latest figures include the dozens of arrests that have been made following terrorist attacks in London and Manchester this summer.
"Significantly, it's the highest number of arrests in a year since they began recording terror arrest statistics back in 2001 after the attacks on the Twin Towers and the Pentagon in the US".
The number of people arrested over terrorism-related offences increased by 68 per cent to 379 in the year to June, the Home Office reports.
Deputy Assistant Commissioner Neil Basu, the senior national co-ordinator for counter-terrorism policing, said: "We would describe this as a shift not a spike".
Only 123 people of the total arrested were charged with an offence, of which 105 were terrorism-related, according to the Home Office quarterly bulletin, released today. As such the data leaves open the possibility that some suspects were arrested multiple times.
The number of terrorism-related arrests in Great Britain in 12 months to June 2017
But most were not, and even without those major incidents, terror would still have been up by 102 on the year before. 189 were released without charge.
By the end of June this year, 204 people in the United Kingdom were in custody for terrorism-related offences in the country.
It also includes the 12 arrests made in relation to March's Westminster Bridge attack and the 23 which came after the attack on Manchester Arena.
Of this number, 185 people - 91% - of them held Islamist extremist views, and ten others (5%) held far-right views.
Later that month, a man from south Wales drove a van into a crowd near Finsbury Park Mosque, killing one.
Supreme Court, he watched some porn with the justices as they decided on a case involving whether porn should be regulated. Nevertheless, Ted Cruz quickly became a trending topic and the butt of a raging internet joke machine.
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Hackers assailed Bithumb with a spearphishing attack, where fake emails and malware are used to try to steal virtual cash. At least one virtual currency exchange was successfully compromised in late May.
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Since customers includes homes and businesses, these numbers do not reflect the full amount of individuals who lost electricity. The company, however, warned it would take longer to restore customers with tornado damage or severe flooding.