Ontario's Special Investigation Unit has concluded there were no reasonable grounds to charge any police officers in connection to injuries sustained by a 34-year-old Toronto man during last summer's G20 summit in Toronto.

SIU Director Ian Scott announced on Monday that the SIU has closed investigation into injuries sustained by Joseph Thomson without laying charges.

Thomson was injured as he was being placed under arrest, Scott said, noting that officers had been permitted to use reasonable force.

"After reviewing all of the new information gathered in the reopened investigation, and in particular the videos, I am of the view that the arresting officers had the lawful authority to arrest Mr. Thomson for committing at least one criminal offence," Scott said in a statement. "The ultimate issue of Mr. Thomson's guilt or innocence will be decided by the criminal justice process."

Thomson was in the area of Queen Street West and Spadina Avenue on June 26 of last year, when the largest demonstration of the week took place. Police allege that he interfered in the arrest of a friend and was subsequently taken into custody.

According to police he was struck in the face by an officer during his arrest and suffered a broken nose. Thomson was taken to hospital for treatment and then released.

The investigation had been closed previously, but reopened in January when new photographs and video came to light.

The SIU originally interviewed eight officers about the incident, but closed the case on Nov. 25. Scott re-opened the case after investigators reviewed new video and still images of the incident.

Eight more Toronto police officers and 22 RCMP officers were interviewed, more video was recovered and nine notebooks were studied before the SIU closed their investigation.

Scott concluded on Monday that the evidence did not suggest excessive force was used during the arrest.

A civilian agency staffed by former law enforcement personnel, the SIU investigates deaths, serious injuries or allegations of sexual assault involving police.