Police are patrolling riverside paths in Wales’ capital, after attacks by youths in balaclavas, including an attempted assault on plain-clothed officers.
Pedestrians and cyclists have been targeted on the Taff Trail in Hailey Park, Gabalfa, and Llandaff.
Concerned parents said their children have been attacked while riding bikes on the trail since June.
South Wales Police has increased patrols on its section of the Taff Trail that runs for 55 miles (88.5km) from Brecon in Powys to Cardiff.
While the force did not have statistics for crimes on the Taff Trail for June, boys aged 13 and 11 were arrested earlier this month.
According to South Wales Police’s crime map, external, the area of Llandaff North received 34 reports of anti-social behaviour in June.
Riverside, another area the Taff Trail runs through, had 18 reports, and Gabalfa had eight.
Speaking at a cyclist safety meeting on 28 July, Insp Tim Ursell said a youth was arrested on the Taff Trail a couple of weeks ago after jumping out “on two of my plain-clothed officers” and was “fully prepared to assault them”.
The force confirmed officers received a 999 call reporting an attempted robbery at 15.45 BST on 23 July near Sophia Gardens.
A 13-year-old from Old St Mellons, was arrested, and following a plain clothes patrol, a second boy, 11, from Penylan, was also arrested.
Both have been released on bail pending further enquiries.
The force identified the Taff Trail along with Bute Park as areas experiencing a higher level of youth anti-social behaviours.