Rallies and marches to mark International Workers Day — also known as May Day — caused little disruption across the country Tuesday as community and activist groups organized a series of events.

However, more than 100 people were arrested in Montreal and several Occupy protesters were arrested in Toronto.

A few hundred public sector workers gathered in front of Prime Minister Stephen Harper's Ottawa office around noon for an anti-austerity protest. Many waved union flags as they chanted, sang and listened to speeches.

The crowd was boisterous but peaceful. They expressed concern about thousands of jobs being lost to federal government budget cuts.

Many of the demonstrators sported buttons that said, "Stephen Harper hates me."

Some in the crowd indicated they were also backing striking students in Quebec.

Union officials said a group of students was barred from crossing from Quebec into Ontario to join in the protest.

In Toronto, members of the Occupy movement held a rally at Nathan Phillips Square at 11 a.m. Attendance was sparse and about two dozen people performed street theatre.

Toronto police on foot, horses and bikes outnumbered the protesters.

A number of Occupy members moved to a downtown park later in the evening and police warned them of a bylaw which prevents camping in public spaces. Three protesters were arrested Wednesday morning when they tried to pitch a tent.

Montreal police clash with protesters

Police arrested more than 100 people after a peaceful May Day rally in Montreal descended into violence. Police clashed with protesters, many clad in black and wearing bandanas over their faces, on Tuesday evening.

Some demonstrators hurled rocks and other objects, including molotov cocktails, at police cars while officers released sound grenades and chemical irritants into the crowd.

Many wore the small red square that represents Quebec's student movement which is opposed to tuition fee hikes, although the rally was not organized by students.

A parallel May Day rally organized by union activists took place without incident Tuesday evening in the Montreal district of Rosemont.

Organizers push for more public services

About 60 black-clad demonstrators tried to start a bon fire in the middle of a busy intersection in Vancouver on Tuesday night, but the protesters quickly dispersed without any arrests after the police riot squad moved in.

Many of the protesters appeared to have been part of a more orderly May Day rally organized by labour unions and supporters of the Occupy movement outside the Vancouver Art Gallery earlier in the day.

A day after the province pulled the plug on slots at Windsor Raceway, a number of employees plan to take part in a May Day march starting at 5:30 p.m. in front of Windsor City Hall.

"It's basically to bring to the public's attention, and bring to the government's attention, to the fact that the folks employed in the horse racing industry strongly disagree with the slot closure," said Ted Mansell, who is with the union representing food and beverage workers at the track.

"These are good-paying, made-in-Ontario jobs that our own government Crown corporation is now eliminating."

Among other causes, organizers say they want to show respect for aboriginal sovereignty, urge more public services, and push for an end to corporate handouts.

Activists had been encouraging workers to call in sick today in order to attend May Day events.

With files from The Canadian Press