(SkyNews) More than 700 potential terror suspects have travelled to Syria and hundreds have returned to the UK, according to Scotland Yard.
Around 350 of the people of "significant concern" who visited the country are thought to have come back and police are arresting nearly one suspect every day.
A record 338 people were detained on suspicion of terrorism offences in 2014/15 - a rise of a third compared to the previous year.
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Assistant Commissioner Mark Rowley, who is in charge of police counter-terrorism efforts nationally, said more than half of the arrests were related to Syria.