MONTREAL - Some people are lashing out at Quebec police in the wake of violent confrontations in which several protesters were injured, including one who lost an eye.

There are allegations police overreacted last week to small groups of rock-tossing protesters by declaring a demonstration illegal, firing rubber bullets at people's heads, and using chemical irritants and mass detentions.

Related accusations had been levelled by some of the participants involved in Montreal protests over recent weeks but they spiked after a particularly violent skirmish with provincial police in small-town Victoriaville last Friday.

Images that emerged from the event showed a small mob beating up on a police officer with punches, kicks and stick-swinging. But many protesters, along with their supporters, are saying the violence cut both ways.

Online, nearly 12,000 people have signed a petition against the police reaction to the series of anti-tuition fee increase protests.

"Let us sign this petition to end a police repression that shamefully flies in the face of democracy and is unwarranted with respect to a student movement that remains essentially a political conflict rather than a judicial exercise," says the multilingual petition.

Last week in Victoriaville, where Quebec Liberals were holding a convention, several police as well as demonstrators were hurt in clashes that lasted several hours. The police officers have since returned to duty although at least two of the students remain in hospital.

There are reports from students in alternative media that some of the 110 demonstrators arrested last Friday were held for up to 10 hours on school buses that transported them from the demonstration, after the vehicles were stopped by police.

A video posted by another student reporter on YouTube showed scenes of the riot, concluding with provincial police detaining students on a bus. In one segment, a helmeted riot-squad officer stands in the aisle of the bus and orders the videographer to turn off his camera.

Sgt. Daniel Thibodeau, a spokesman with the Quebec provincial police in Montreal, said he could not comment on the specifics of the arrests in Victoriaville or how long it took to process the demonstrators.

"I don't have particulars on how they were released or transported," he said. "I do know that there were 101 (arrested) aboard three buses." He said processing lasts as long as it has to when someone is arrested.

He also said it would be "imprudent" to comment on allegations that police fired rubber bullets directly at protesters' heads, without seeing actual footage or the incident report.

Thibodeau said police do not target people's heads when firing rubber bullets.

"A lot of projectiles were thrown that day and people were hit with various items coming from the protesters themselves and not necessarily from officers," he said. "The head is something that's not aimed at intentionally by our officers -- of course for the obvious reason that it can have some serious health consequences."

The Canadian Security Intelligence Service also refused to comment Monday on a newspaper report that its agents were tracking members of some groups -- including elements like the Black Bloc, one hardline pro-Quebec independence group, and anarchists -- taking part in the student protests.

"We do not comment on operational questions, speculative or otherwise," said Tahera Mufti, an agency spokeswoman in an email.

However, analyst David Harris said in a telephone interview that he would be surprised if the intelligence service did not keep an eye on the protests given recent developments in Quebec, and its mandate to keep track of potential threats to national security.

"I'd be wondering what people were doing with my tax money (if they weren't monitoring)," said Harris, who was once the agency's chief of strategic planning.

"When you have features including violence, indications of certain kinds of well-organized aspects that might be associated with violence, you must, it seems to me as a government in general, engage in some serious reflection and analysis about that. If you come up with a negative, you've resolved some issues that allow you to better focus resources."

Harris, who is now director of the international intelligence program with Ottawa-based Insignis Strategic Research Inc., stressed he did not have any inside information on CSIS activities in relation to Quebec's protests.

"I'd suggest that the record of the Black Bloc is notorious enough to invite CSIS's scrutiny," he said of the radical organization that has been linked to several incidents, including the G20 protests in Toronto in 2010.