A massive protest has closed a swath of Toronto's downtown core. Police say University Avenue will likely be closed until after Tuesday's morning rush hour at the earliest.

"Traffic congestion on the roadways and within the transit system is to be expected," police said in a Monday evening news release, adding that people should consider alternate routes.

Tamil protesters have converged on University Avenue, outside the U.S. consulate, since Sunday evening, forcing police to close the street from College to King Streets.

Queen and Dundas Streets are also closed from Spadina Avenue to Bay Street as a result.

CTV Toronto's Chris Eby said at suppertime the shutdown of University is affecting other north-south thoroughfares such as Bay and Yonge Streets. Those are jammed, he said.

The protesters are mostly from Toronto's Tamil community. They arrived on the scene overnight with blankets and drums. There is a heavy police presence in the area but the protest has been a peaceful one.

The Tamil community has staged several protests in an effort to persuade the Canadian government to denounce the Sri Lankan government's actions in the country's civil war against its Tamil residents.