MONTREAL - Amid heavy police presence, a group of several thousand protesters marched through downtown Montreal Friday against the Charest government's planned tuition increases.

Protesters were denouncing a new offer from Premier Jean Charest that would stretch the hikes over seven years and enrich the loans and bursaries program.

The march was entitled: "It's not an offer, it's an insult!''

It began shortly after 8:30 p.m. at Parc Emilie-Gamelin and was, for the most part, peaceful. Protesters weaved their way toward St. Laurent Boulevard and Ontario, where they were met by a wall of riot police. They were eventually rerouted by police west onto Ontario Street and the march continued into the downtown core.

Police declared the march illegal at about 10:20 p.m., saying protesters had thrown objects at officers. But the march continued, peacefully for the most part, and police allowed it to proceed.

One window was broken at the National Defence building on Ste. Catherine St., and there were reports on Twitter that the vandal was chastised by peaceful protesters.

By about 11:30 p.m., police had made about 30 arrests for what they called isolated illegal acts.

It's unclear whether Charest's offer will change anything. At least six demonstrations were held in the province on Friday, including one in Quebec City that ended with several dozen arrests.

About 170,000 students are still avoiding their classes - but most have chosen to return to school over the 11-week dispute.

Charest's proposal is set to be discussed at student assemblies over the weekend. More protests are also planned this weekend, along with votes on returning to school.