A Melbourne teen arrested after police found explosives at his home pleaded guilty on Monday to a terrorism-related charge, highlighting concerns about youth radicalization following last week's arrest of a 15-year-old Sydney boy in police raids.

The 17-year-old was planning an attack using improvised explosive devices, police said in May when they raided his home in Greenvale, 20 kms (12 miles) north of Melbourne.

The boy, who could not be identified because of his age, pleaded guilty to a single charge of "engaging in an act in preparation for, or planning, a terrorist act," the Australian Associated Press reported from the courtroom.