The Department for Child Protection and Family Support fears for the safety of 12-year-old Clive Hart, who has now been missing for nearly three weeks, and has appealed to the public for help.

"Clive was last sighted in Warnbro on 15 September and, since then, the department has been working with police to locate him and is now appealing for the public's help," a departmental spokeswoman said.

A recent photograph of Clive Hart, missing since September 15. If you see him, call police immediately on 131 444.

Officials believe Clive could be in Mandurah, Cockburn or Armadale.

He has dark brown hair and brown eyes and was last seen wearing long light khaki chinos, a black T-shirt and black shoes.

Anyone who knows where Clive is now should call police immediately on 131 444.

Anyone with information on his past movements should call Crime Stoppers on 1800 333 000.a departmental spokeswoman said.