MONTREAL -- Concern about the credibility of a high-profile witness is forcing a brief delay for Quebec's corruption inquiry.

The inquiry was expected to begin focusing on the scandal-plagued municipality of Laval on Wednesday, with a suspended city manager taking the witness stand.

But inquiry counsel Sonia LeBel emerged after an hour-long delay to announce that there were serious concerns about Gaetan Turbide, the senior city official.

LeBel said the concerns were sparked by information received shortly before the inquiry was scheduled to sit.

"At 9:15 this morning, inquiry counsel learned information that makes them seriously doubt the credibility of the next witness Gaetan Turbide," LeBel said.

The information was enough for the inquiry to cast doubt on the Turbide's credibility as an inquiry witness, at least for now.

It's unclear why concerns about witness credibility would stop the inquiry now.

Such concerns have been a concern throughout the process -- where chronic memory gaps, shifting stories, and improbable explanations on the witness stand have occasionally elicited expressions of frustration from the judge and counsel.

This week, a former political organizer and engineering executive admitted to lying under oath about whether he owned or rented his summer cottage. A day later, he admitted to having swapped a home with a Hells Angels biker. This was after that detail had appeared in a local newspaper.

Earlier this year, Martin Dumont, whose testimony helped bring down the former mayor of Montreal, also admitted to making up an anecdote.

Other witnesses have suddenly revised basic details about their testimony upon being confronted with new facts by lawyers.

For reasons not explained Wednesday, though, concerns about Turbide's credibility were deemed to be a show-stopper.

Turbide's testimony was to come after his former boss, ex-mayor Gilles Vaillancourt, and 36 others were arrested in massive corruption sweep in Laval, a suburb just north of Montreal.

Vaillancourt ruled over Laval for some 23 years and earned himself the nickname the "Monarch of Laval."

He was formally charged last week with a dozen corruption related charges, including two counts of gangsterism. The list of charges intimated that the municipal government was run like a criminal organization. The ex-mayor has said he will fight to restore his reputation.

Turbide was not among those arrested last week.

As the arrests were taking place, the Crown was requesting a publication ban on Turbide's inquiry testimony to guarantee a fair trial for those charged criminally.

The inquiry denied the request but offered up other measures to ensure the criminal proceedings were not hampered.

LeBel said the inquiry will continue with another witness -- Jean Roberge, another senior Laval bureaucrat. A similar publication ban request will be discussed before his testimony begins.

The inquiry should resume at 2 p.m.