The man once known as the "King of Laval" will plead guilty today to fraud charges in connection with allegations dating back to his time as mayor, sources tell CBC's French-language network, Radio-Canada.

Gilles Vaillancourt, who ran Quebec's third-largest city for more than two decades, was arrested in 2013 as part of a sweep by the province's anti-corruption unit, known as UPAC.

The prosecution and Vaillancourt's defence team have agreed to propose a sentence of six years in prison and the reimbursement of $9 million, Radio-Canada's Marie-Maude Denis has learned.

The 75-year-old will plead guilty to fraud on the government, breach of trust, conspiracy and fraud.

Gangsterism charge suspended

It's also understood that Quebec's Director of Criminal and Penal Prosecutions has agreed to suspend the gangsterism charges against Vaillancourt as part of the agreement, which must be approved by a judge.

The longtime mayor was arrested along with 36 others in March 2013, when UPAC raided Laval city hall, banks and Vaillancourt's residence in a sweep.

He was originally facing 12 charges including conspiracy, fraud, influence peddling, breach of trust and gangsterism.

Thirty-three of his co-accused are still slated to stand trial.

Vaillancourt was mayor of Laval for 23 years, from 1989 to 2012.

He is set to appear at the Laval courthouse Thursday morning.

Francine Charbonneau, the minister responsible for Laval, said she believes a plea will help turn the page for Laval. (Radio-Canada)

Laval living in shadow of Vaillancourt

The minister responsible for Laval, Francine Charbonneau, said Wednesday that Laval had been living in a shadow since Vaillancourt was charged three years ago.

Speaking to reporters after a cabinet meeting, Carbonneau said that the plea, if it happens, would be a step forward.

"It will turn the page, but I'm waiting anxiously to see tomorrow how this will end," she said.

Charbonneau added that Vallancourt's actions had put a "grey cloud" over all elected officials and hurt the public's confidence.