Security cameras in a cannabis dispensary in Canada have captured the moment a man used a bong to fight off three would-be bandits wielding cans of bear spray.

CCTV footage showed three men with their heads covered enter the premises in Tyendinaga, Ontario, before one of the men sprayed a man and woman working behind the counter.

The staff ducked, before the man emerged clutching a bong that he used to fend off the men.

Tyendinaga Police appealed to the public to help identify the "four males, believed to be of middle eastern decent (sic)" that attempted to rob the Recreational Cannabis Farmers Market.

"They were met with great resistance by the store clerk and despite being sprayed with bear spray, the clerk who is from Tyendinaga Mohawk Territory managed to successfully fight them off and force them from the store," they said in a Facebook post.

"The suspects then fled the scene westbound on Old Highway 2 in a white SUV."

In late August the same police department had also sought public assistance after "an unknown suspect committed an armed robbery at the 'Medibles' Cannabis Dispensary".