A prison guard was arrested reportedly with 50 yaba tablets from the city on Saturday night. The arrestee is M Saiful Islam, 22, a prison guard of Chittagong Central Jail. Officer-in-charge of Kotwali Police Station Mohammad Mohsin said a police team intercepted a CNG-run auto-rickshaw in Kadamtali Flyover around 7:45pm and arrested Saiful along with the contraband tablets.