Ontario's police watchdog says it is investigating injuries sustained by a woman participating in an Occupy Toronto protest after tension between the Toronto Police Service and the group of demonstrators ratcheted up over the weekend.

Ontario's Special Investigations Unit said Monday it would probe the circumstances behind the injuries to a 36-year-old woman, who was involved in an interaction with police during a protest on University Avenue Friday night.

Angela Turvey, one of the four protesters involved, suffered a fractured eye socket and broken nose during the confrontation.

Occupy Toronto alleged Turvey and three other demonstrators were "brutally beaten" after police asked them to dismantle an encampment at 361 University Ave., near Osgoode Hall, on Friday.

Video uploaded to YouTube appears to show a police officer trying to restrain Turvey as she cries out, face down on the pavement. At one point, she turns her face towards the camera and it looks as if part of her face is swollen.

Turvey was charged with obstructing a police officer.

John Erb, 44, faces a string of charges including assault with intent to resist arrest and possession of marijuana.

Craig Poirier, 35, and Alice Evonic, 19, were also arrested during Friday's incident.

Two more protesters were arrested Sunday after holding a rally to denounce the arrests.

The pair was charged with mischief and interfering with traffic after demonstrating outside Toronto Police Service's 52 Division headquarters.

Speaking to reporters after a court appearance on Saturday, Turvey's lawyer, Michael Leitold, called for the SIU to investigate his client's injuries.

The SIU said on Monday that a total of four investigators have been assigned to the case.

The SIU is asking anyone who may have witnessed the incident to call the lead investigator at 416-622-2314.