The searches targeted Gilles Vaillancourt, the powerful mayor who has enjoyed a 23-year reign at the helm of Laval, Que., the third-biggest municipality in the province.
About 70 officers from the provincial police anti-corruption unit participated in the operation; Vaillancourt was not home when the officers arrived there, his press secretary said.
Laval city hall was evacuated when the raids began, around 4 p.m.
A spokeswoman for the anti-corruption unit wouldn't say what was being seized but she confirmed material was gathered as part of an ongoing investigation.
"There is an investigation underway and the seizures are taking place to help along that investigation," said Anne-Frederick Laurence.
Vaillancourt is not accused of any crime.
The mayor has in the past expressed outrage on occasions when accusers tied him to allegations of crooked cash dealings.
A powerful figure in municipal politics, Vaillancourt has been in office since 1989 although his reign has become increasingly marked by controversy.
A news report last month on illegal campaign financing said a onetime fundraiser for the provincial Parti Quebecois claimed to have received $10,000 in cash from Vaillancourt during a 1994 election.
It wasn't the first time Vaillancourt had been forced to deny such activities. He also denied offering money during a provincial election to Liberal Vincent Auclair and former PQ cabinet minister Serge Menard.
The anti-corruption unit was created by the former Charest government amid scandals in recent years. It has mostly targeted people from the construction industry and some lesser-known political figures in smaller municipalities.
There have also been criminal charges laid against high-ranking members of Montreal Mayor Gerald Tramblay's inner circle. This week the mayor suspended three Montreal municipal employees and temporarily froze new construction contracts.
But Tremblay has brushed off demands for his resignation, following sensational allegations at Quebec's ongoing corruption inquiry.
A witness at the inquiry has testified about systemic corruption. The former construction boss told the inquiry that companies operated as a cartel that boosted the price of construction contracts, with the help of corrupt local bureaucrats and the participation of the Italian Mafia.
Lino Zambito alleged that companies took turns winning what were supposed to be competitive bids; bureaucrats helped the companies take advantage of loopholes and further drove up the price tag; and a percentage of all the profits went to corrupt officials, the Mob and the Montreal mayor's party.
The inquiry will not be hearing witnesses for the next few days.
Zambito returns to the witness stand on Oct. 15. He has promised to share details about schemes that took place at the provincial level.
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