Mayor Tremblay says he should have been told years ago about secret RCMP video showing construction company bosses secretly giving cash to the mafia.

The videos were shown at the Charbonneau commision looking into construction corruption in Quebec.

They show construction executives bringing wads of cash to mafia bosses, who, among other things, stuff the money in their socks.

The opposition at Montreal city hall wonders aloud how the mayor could not have known what was really going on.

"This guy has been the mayor of Montreal for the last 11 years", says Project Montreal leader Richard Bergeron.

"Once again the mayor of Montreal is looking for an excuse", said Vision Montreal leader Louise Harel.

Tremblay wants the province to make it tougher for construction companies with a questionable past to get contracts.