Montreal's ruling municipal party has passed measures at city council that it says will reduce the risk of corruption in public works contracts and political financing.

Council voted 35-15 in favour of the first of several Union Montreal motions on Monday. Opposition party Vision Monteal voted against, while councillors from the third party, Projet Montréal, walked out before the vote, calling the debate a "masquerade."

The tense council meeting saw the two main parties hurl accusations of corruption at each other.

Witnesses at the Charbonneau commission, Quebec's ongoing corruption inquiry, have testified that hundreds of thousands of dollars in kickbacks on city construction contracts were paid either to Union Montreal or to the city's executive committee, a point opposition councilors harped on Monday. Senior city bureaucrats also accepted bribes, the inquiry has heard — one by his own admission.

Mayor Gérald Tremblay retorted that "collusion and corruption" were rampant from 1994 to 2001, when Vision Montreal was in power. He repeated his avowal that he will not resign.

"The opposition leader is constantly proclaiming her political virtuousness," Tremblay said of Vision Montreal leader Louise Harel. "Should Vision Montreal politicians not have been aware of the collusion and corruption in that era? Did they keep their eyes closed?"

Harel replied that Tremblay's statements were "pathetic."

"It's worse than ironic. It's really ridiculous to not take responsibility," she said.

Projet Montréal said Union Montreal's anti-corruption plan has "no credibility" given the rampant accusations of graft against city administrators. Its politicians walked out of the meeting to let the other two parties squabble, leader Richard Bergeron stated.

"We'll let Montreal's two corrupt parties dirty each other," he said.

The stormy council meeting was matched by tensions outside City Hall. There, a sizeable group of protesters gathered to demand amnesty for people arrested during last spring's student-led uprising in Quebec.