MONTREAL - Federal lawyers say a high-profile Quebec corruption inquiry can't compel the RCMP to sift though, and share, a treasure trove of information on the Mafia.

Lawyers representing the Mounties were in a Montreal courtroom Wednesday fighting off demands for information from Quebec's Charbonneau inquiry.

Lawyers for the inquiry want access to the massive amount of evidence gathered during Operation Colisee, a police probe that concluded in 2006 and is considered the largest such investigation into the Mob in Canadian history.

The Charbonneau inquiry says the information is necessary for its probe into allegations of corruption involving the construction industry, organized crime, political parties and the awarding of public contracts.

But the RCMP, a federal body, argued that it can't be compelled to answer to a provincial commission. It has also said the Quebec request is too vast and complicated to manage. The force has said, however, that it is ready to co-operate with the commission in other ways.

"We are displeased with the attitude of the RCMP and we have said so," said Sylvain Lussier, the chief prosecutor for the Charbonneau Commission, said outside the courtroom.

"This is not a fishing expedition -- we have very precise requests... And the specific requests have not been answered."

Federal lawyers argued Wednesday against a subpoena for the information. They said it should remain solely in the purview of law enforcement.

They also said the request from the corruption inquiry was too broad and that fulfilling it would require too much time, manpower and money.

The RCMP said its information has already been archived and that much of the 1.5 million wiretap calls -- and thousands of photos and videos -- deal with evidence that is beyond the scope of the provincial commission.

They argued that many of the people caught in the four-year probe have nothing to do with the construction industry and there are rules governing who can access wiretap information.

"The commission doesn't know what it's looking for," said federal lawyer Claude Joyal. "The RCMP's mandate isn't to serve the commission, it is to run criminal investigations."

Operation Colisee led to the arrest of the braintrust of Montreal's powerful Italian Mafia, including the late Nicolo Rizzuto Sr., who was murdered in November 2010.

The charges laid during subsequent trials included gangsterism, drug-trafficking, money-laundering and illegal gambling.

Information gathered at the time about the construction industry and the Mafia was never released.

Joyal told the court the evidence that was sealed had nothing to do with construction -- that it wasn't part of the RCMP investigation.

But members of the Charbonneau inquiry call their subpoena an evolving request. They say it will become more specific once they've examined certain documents, and after information is gleaned from calls to the commission's hotline.

Quebec lawyer Claude Chartrand said he found it surprising that the RCMP would manage to conduct such a complex investigation and bring it to trial -- and would now call the request for information too challenging.

"I have difficulty with the idea that ... it's unmanageable," Chartrand said.

Commission lawyers have said it's important to have access to the RCMP evidence as soon as possible if the Charbonneau probe is to complete its mandate by October 2013. The inquiry headed by Quebec Superior Court Justice France Charbonneau is to begin hearing from witnesses this fall.

The commission is already doing preliminary work, such as gathering evidence.

"We are conducting the inquiry. It would certainly be helpful if we have that information but we are (already) gathering a significant amount of information at the present moment," said Lussier, who represented the federal government during the Gomery inquiry on the sponsorship scandal.

"It would be very pleasant to have as well the information that is in the possession of the RCMP."

Justice Guylene Beauge asked Joyal, hypothetically, what would be needed to make the task more manageable for the RCMP.

Joyal returned in the afternoon to say the request should include specific information -- like the full names of people of interest -- as well as a reasonable deadline for transferring the evidence.

The case continues Thursday.