The estimates are found in internal provincial public security documents obtained by QMI Agency.

Bill C-10, the federal Safe Streets and Communities Act, toughens sentences for a variety of offenses.

The law reduces the use of conditional sentences, such as house arrest, provides harsher penalties for young offenders, and makes it more difficult to get a pardon.

Quebec has opposed the bill from the start and plans to soften provisions wherever possible. Quebec also said it will delay implementation by as much as seven years.

The province predicted Bill C-10 could swell the population of the 18 provincial jails by nearly 20%. The report noted the facilities are already filled to 96% capacity.

"Such an increase represents additional costs of up to three quarters of a billion dollars in capital expenditures for the construction of new detention facilities," the report said.

The department said an additional $80 million a year will be needed for operating and staffing costs.

Justice Minister Jean-Marc Fournier has already told the federal government the province will not top up the $543 million already earmarked for jail renovation, expansion and construction.

"It's out of the question for the Quebec government to foot the bill for the construction of new prisons," said David Couturier, a spokesman for Fournier.

Federal estimates of the effects of Bill C-10 are lower than those of Quebec.

The federal numbers say Bill C-10 would add 2,500 more inmates to provincial jails per year and cost an additional $137 million annually.