A 57-year-old judo instructor is accused of assaulting four of his students at a Richmond Hill martial arts club, York Regional Police say.

Officers arrested the man at the martial arts club Thursday as part of an investigation that began last May.

Police said investigators from the crimes against children unit received information that led them to look into alleged abusive behaviour at the martial arts club.

Police didn't identify the club.

The instructor is accused of assaulting four boys between the ages of six and 15. The charges indicate a weapon was allegedly involved.

Investigators believe there may be additional victims.

Police said Viktor Sokolovski, a Richmond Hill resident, is charged with four counts of assault with a weapon, eight counts of assault, and a single count of uttering death threats.

Sokolovski is in custody and is scheduled to appear in court in Newmarket on Friday.

Anyone with information about the allegations is asked to call York Regional Police at 1-866-876-5423 ext. 7075 or Crime Stoppers anonymously at 1-800-222-8477.

People can also e-mail the investigators directly at emailcacu@yrp.ca.