In the video, Vancouver Police Const. Ismail Bhabha appears to punch cyclist Kharazi Andisheh Akhavan in the head.
When Akahavan protests, the officer says he punched him because he was resisting arrest, but Akhavan denies it, saying there was no reason to punch him.
The incident was captured on camera by a friend of Akhavan's who was passing by. The video of the incident was later posted to Facebook, where it quickly began gathering comments expressing outrage and was shared widely over the following week.
B.C.'s Police Complaint Commissioner Stan Lowe said he was first made aware of the incident by calls from the media and, after monitoring the story, he decided it warranted investigation by his office.
Lowe says West Vancouver Police Department Chief Const. Peter Lepine agreed this week to conduct an external investigation into the incident.
"The commissioner has determined that it is in the public interest to exercise his discretion pursuant to the Police Act to appoint an external police agency to investigate this incident in order to maintain public confidence in the police complaint process," said a statement issued by Lowe on Tuesday morning.