Police have issued an amber alert for a missing three-year-old B.C. boy, and say he may be with a convicted criminal.

Kienan Hebert of Sparwood, B.C. is believed to have left his family home off Highway 43 some time overnight. He was discovered missing at 8:30 a.m.

An amber alert was issued late Tuesday afternoon. RCMP say the little boy may be with 46-year-old Randall Hopley, who drives a 1987 brown Toyota Camry with the B.C. licence plate 098RAL.

Hopley has previous convictions for sexual assault, assault, theft and break and enter.

Police say that Hopley and Hebert have no previous relationship. Hopley is white and has dark hair.

Hebert is believed to be wearing Scooby Doo boxer shorts and could be carrying up to three blankets with him.

"There's a history that Kienan does sleepwalk, but in past incidents, he's never exited the house. Other than that, there's not much else (to explain his disappearance)," RCMP Cpl. Dan Moskaluk said.

RCMP officers started a search effort including an air services helicopter and a search dog unit, but have not found any sign of the boy.

Anyone with information on Hebert's whereabouts is asked to call the Elk Valley RCMP at 250-425-6233.

(With files from ctvbc.ca and The Canadian Press)