Arrests of British teenagers on terror offences have tripled in the past year, with authorities fearing the rise of Islamic State (IS, formerly ISIS/ISIL) is responsible for the growing number of youngsters attempting to flee to Syria.

Forty-six 18 to 20 year olds were held under terror laws last year, the Telegraph reports – a marked increase on the 15 held in 2013.

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This matches an overall increase in the number of people arrested on suspicion of terrorist activity, with a total of 298 people held – a 30-percent increase on the previous year.

More than 700 Brits are believed to have traveled to Syria to join the IS militant group, with approximately 200 returning to the UK.

Prime Minister David Cameron has recently said the lure of Islamic State is responsible for the spate of arrests.

Cameron came under fire from Islamic groups and other politicians after he accused members of the Muslim community of “quietly condoning” the extremist mentality, which was encouraging more young people to become radicalized.

He also told the relatives of people suspected of having traveled to Syria that they should stop “finger pointing” and placing the blame on security services.

His sentiments were echoed by Home Secretary Theresa May, who urged those at risk of radicalization not to be duped by the supposed “glorious cause.” If they left, they would be “putting your life and lives of your families at risk,” she said.

The figures come as a Pakistani Islamic cleric launched a “counter-terror” curriculum to help tackle the threat of radicalization and challenge the message of extremist groups.

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On Tuesday, Muhammad Tahir-ul-Qadri said he had written the curriculum, which appears in English, Arabic and Urdu, to provide an alternative narrative to the extremists.

“This isn’t a process that started yesterday,” he said. “That radicalization began to happen 30 years ago".

“You can see this gradual process of grooming by extremist groups such as IS and we must address that, and the arguments used by IS to justify their criminal, terrorist activities.

“You have to tell young people that IS and others are giving them the wrong interpretations of Islamic concepts such as jihad.”