There have been more than 600 arrests in Toronto this weekend, as the Integrated Security Unit took aggressive action to keep G20 protesters at bay on the final day of the summit.

Overnight, about 1,000 additional Ontario Provincial Police officers were transported downtown, bringing the total number of security for the international summit to 20,000.

One of the more dramatic raids happened at a student residence building on Bancroft Avenue, on the University of Toronto campus. Approximately 70 people were taken into custody Sunday morning.

Police removed bags of clothing and some street-type weapons.

"Items seized have been bottles with unknown substances, brick bats, sharpened sticks," said Const. Rob McDonald. "Items you don't need for a weekend in Toronto."

CTV News Channel footage showed men and women of varying ages being escorted by police, taken away to detention. Many of them had their hands bound in flex ties.

Some of the people arrested had a phone numbers written on their bodies, possibly for legal counsel. Representatives of the Canadian Civil Rights Association were on hand, taking notes.

Police roaming the streets on bicycles or standing at major intersections were stopping suspected protesters to conduct "investigative searches" across the downtown area Sunday morning.

Police were apparently confiscating items they believe could be used to destroy property, or that could be used in a confrontation with security forces.

In other developments:

• Sources tell CTV that police have arrested several individuals in a vehicle for weapons-related offences. Molotov cocktails and anarchist shirts were seized.

• Two cyclists taking part in a larger bike protest being led by police were detained around 2:20 p.m.

• Well-know anarchist Chris Bowen was among the arrests at a rally outside the G20 prisoner processing centre turned violent Sunday afternoon. A crowd of at least 100 people had gathered at the detainment facility to support those arrested this weekend.

Some had complaints about the way they were arrested, and one called it a "catch-and-release" system.

Bridie Wyrock, a 20-year-old woman from Cleveland, told CTV News she was taking part in a peaceful sit-in on the Esplanade in front of the Novotel hotel when she and fellow protesters were surrounded by dozens of police in full riot gear.

"They had picked me up, and had thrown me to the ground and slammed my head on the ground twice, completely unnecessarily," she alleged. "They put their arm around the back of my neck, choking me, and put (plastic) ties (around my wrists) so hard that I still have bruises and marks."

Wyrock found herself facing charges of breaching the peace, mischief and obstructing traffic -- all of which were dropped by Sunday afternoon when she was released after her 19-hour detainment.

The courts remained open through the weekend to handle G20-related arrests.