UK officials say number of terrorism arrests at record high this year

British officials say the number of people being arrested on suspicion of terrorism-related crimes has reached a record high.

The Home Office figures released Thursday show 299 people were arrested in the 12 months that ended in March. Officials say that represents a 31 percent increase over the previous 12 months, and is the highest figure since records started being kept after the September 11, 2001, attacks in the United States.

Officials also report a "marked increase" in the number of suspects who are either British or dual nationals.

Police have warned that the Islamic State group has been adept at winning followers inside Britain via social media.

Not everyone arrested on suspicion of terrorism is charged with a crime.