More than 100 people were arrested at the end of a long day of protests in Montreal that saw tens of thousands of people take to the streets over several hours to mark the 100th day of a student movement against tuition hikes.

Carrying signs, chanting slogans and wearing the student movement's red felt square, most protesters followed a pre-approved route submitted to police, as required by Quebec's new protest law. But encouraged by the more hardline CLASSE student group, a minority of protesters broke off from the main crowd in a symbolic defiance of Bill 78.

At least one splinter march was declared illegal by police shortly after 9 p.m., because according to police, protesters were throwing projectiles at officers, walking on an unannounced route, and some were wearing masks.

Police said many of the protesters were from anarchist groups not directly connected to protesting student groups.

Small clashes between protesters and police followed, some involving protesters being pepper sprayed, and four people were taken to hospital with minor injuries.

Police and witnesses confirmed that one of the injured was a protester who was the victim of a hit-and-run driver.

CLASSE spearheaded Tuesday's march, aided by Quebec's largest labour federations. The province's two other main student groups, FEUQ and FECQ, also rallied their supporters.

CLASSE said Monday it would direct members to defy Bill 78, Quebec's emergency legislation.

The special law was adopted last Friday, suspending the winter semester and imposing strict limits on student protests. Organizers have to submit their itinerary to authorities in advance, or face heavy fines.

CLASSE spokesman Gabriel Nadeau-Dubois said the special legislation goes beyond students and their tuition-hike conflict.

"We want to make the point that there are tens of thousands of citizens who are against this law who think that protesting without asking for a permit is a fundamental right," he said, walking side by side with other protesters behind a large purple banner.

"If the government wants to apply its law, it will have a lot of work to do. That is part of the objective of the protest today, to underline the fact that this law is absurd and inapplicable."

At a news conference, Quebec Public Safety Minister Robert Dutil cited a list of cities with equally tough rules for organizing protests. Dutil listed Geneva, Toronto, New York, Los Angeles and Spain as jurisdictions that require far more than eight hours' notice — up to 40 days, in the case of Los Angeles — in order to hold a protest.

"Other societies with rights and freedoms to protect have found it reasonable to impose certain constraints, first of all to protect protesters, and also to protect police," Dutil said.

Student Hugo De Montigny said he was marching because he wants to be heard, on "everything, from [Bill] 78 to tuition."

"Sometimes if a government refuses to listen to the people, we have to make them listen to us," said De Montigny, adding he's prepared to lose his semester over the tuition conflict.

"We still have to fight. It's not because they say 'sit down' that you have to sit down."

Student Jenny Markova said the tuition movement has grown beyond a dispute over school fees.

"You can see that there is not only just students, but a big part of the general population that is here today. We're trying to say no to a lot of things that the government has done, so hopefully they'll get the message today."

Former Bloc Québécois leader Gilles Duceppe joined the march, urging Quebec Premier Jean Charest to relaunch talks with students.

Duceppe also disagrees with Bill 78, but said he won't support breaking the law.

"I am not for the attitude of disobeying the law, because we are not in India in the time of Gandhi, nor under the apartheid like Mandela — but on the other side, there is certainly a lack of respect of democracy from the government," he said.

Spontaneous casserole protest heard through city

On Tuesday evening, Montrealers in several urban neighbourhoods took to the streets with pots and pans, banging to support Bill 78 protests.

Police arrest protesters during a demonstration against tuition fee hikes in Montreal on Tuesday. (Ryan Remiorz/Canadian Press)

The "casserole" movement mushroomed over the weekend via social media networks.

On Tuesday night at 8 p.m. hundreds of people in Villeray, Mile-End, Petite-Patrie, the Plateau and St-Henri were seen — and heard — banging on their kitchenware.

Tuesday's protest comes on the heels of a chaotic May long weekend, in which thousands of students and their supporters took to the streets each night, sometimes clashing with police.

The first student protests were Feb. 17, when there was a boycott of classes at CÉGEP du Vieux-Montréal.

Police issue warning: obey the rules

In a news release, Montreal police said the force respects the right to demonstrate but reminded protesters that the march would be declared illegal at the first sign of violence or other infractions.

Police issued a list of rules, including a reminder to protesters to disperse if they hear an announcement from police declaring the gathering illegal.

"If you have not heard the announcements and you see the police intervention squad, get out of the way," the release said. Their presence "means the demonstration has been declared illegal and the police are ready to intervene."

Earlier Tuesday, at Montreal's Pierre Elliott Trudeau airport, police were stopping and searching some vehicles, and there was a heightened presence of police at the airport terminal.

Police would not say if the increased visibility was tied to a specific threat, however, they did say the extra measures were intended to make airline passengers feel safer, in light of concerns around the student protests.

New Yorkers, Parisians march in solidarity

Related events were organized Tuesday in New York, Toronto, Calgary and Vancouver, which saw only a small group of people show up to protest. In France, a few hundred congregated near Paris's famous Notre Dame Cathedral.

The New York demonstration was organized by members of the Occupy movement along with some student groups.

Brooklyn College political science student Biola Jeje said her school – part of the City University of New York (CUNY) – launched its own red square campaign in April, to fight tuition increases.

"When we heard what happened, it was only natural for us to want to organize, and get involved and do something here in the city in support of Quebec."