MONTREAL - Police in Montreal have arrested three 19-year-olds for vandalism Monday morning, believed to be in connection with the ongoing tuition protests.

Police rounded up a duo of young men after 5 a.m. for breaking and entering the CEGEP du Vieux Montreal. Another 19-year-old man was arrested for mischief later Monday morning.

A police spokesman says windows were smashed and what appeared to be Molotov cocktails were also found inside the offices of several Quebec cabinet ministers, including the Saint-Laurent borough office of provincial Justice Minister Jean-Marc Fournier and Seniors' Minister Marguerite Blais on St. Jacques St. in Saint-Henri.

Nobody was injured, but at least one building had to be evacuated.

Along with the vandalism, graffiti in the form of red squares was also painted on the sidewalks outside.

Two buildings on Beaubien in Anjou were also vandalized, as was a building on Cote-des-Neiges not far from the Universite de Montreal.

The red square has become the symbol of students who have been staging protests against the Quebec government's plan to hike tuition fees over the next five years.

In another series of incidents Monday morning which might be related to the tuition protests, three of Montreal's metro lines were forced to close temporarily for up to half an hour as bricks were tossed onto the tracks and riders repeatedly pulled emergency stop levers.

"We found bags of bricks on the rails, so therefore we advised police and police are on the case," said STM spokesperson Isabelle Tremblay.

Police would not say if certain student groups were being investigated in relation to the metro disruption.

"Since these events all happened at the same time, we're talking about what seems like a concerted act, so in this case an investigation has been opened by the Montreal police department," said Anthony Cantelmi of the Montreal police.

Thousands of students have staged walkouts and blocked entrances to classrooms in the past few weeks.

Seven people were arrested Friday shortly after a group broke into and vandalized Education Minister Line Beauchamp's office in Montreal.

Frustration levels are rising but vandalism isn't the solution, said Leo Bureau-Blouin, president of Quebec's Federation of College Students.

"I don't think the subway or the bridges are the right target for the students," he said. "We should concentrate our pressure on Liberals. The government; that should be our main target."

The CLASSE student group held a press conference Monday to discuss the tuition hike issue. The group is the only of the three not to be invited to discuss university financial administration with Education Minister Line Beauchamp.

The CLASSE was not invited because they have failed to denounce violence, said Beauchamp.

Group leader Gabriel Nadeau-Dubois said that he could not denounce violence because he cannot speak for the students on that issue.

He also denounced Beauchamp's statement that she would not discuss the possibility of cancelling the tuition hikes in any talks about university funding.

"We want to remind Madame Beauchamp that those issues are completely related, that it will be impossible to talk to one without the other," said Nadeau-Dubois.

With a file from The Canadian Press