OTTAWA — Canada's crime rate fell last year to its lowest level in nearly four decades, a statistic that opposition MPs held up as proof the governing Conservatives don't need to spend billions on new jails.

Data released Thursday by Statistics Canada shows the crime rate continued a 20-year decline last year, dropping five per cent from 2009 and hitting the lowest level since 1973.

The homicide rate was the lowest since 1966.

The statistics agency said the overall police-reported crime rate is still following a long-term downward curve, despite the alarm bells from the Harper government over the need for tough-on-crime legislation.

The agency said an index which measures the severity of crime fell six per cent in 2010. The crime severity index is at its lowest point since 1998, the first year for which such data are available.

The Conservatives, though, still want to pursue a crime crackdown. In the past they have brushed off the police-reported crime rates, saying many crimes don't get reported and thus undermine the statistics.

Earlier this year, the Conservatives reluctantly released rudimentary cost estimates for a suite of criminal justice legislation. The total five-year cost of 18 justice bills was listed at $650 million -- although the Parliamentary Budget Officer has said the cost of just one of those bills would be several billion for Ottawa alone.

"Not only are the costs outrageously high, but as the StatsCan report shows, they are also at odds with the reality of declining crime in Canada," Liberal MP Carolyn Bennett said Thursday.

"How can the government justify these policies and these expenditures in the face of today's facts?"

Justice Minister Rob Nicholson wasn't available for an interview.

His spokeswoman shot back at the Conservatives' political opponents.

"Unlike the opposition, we do not use statistics as an excuse not to get tough on criminals," Pamela Stephens said in an email.

"As far as our government is concerned, one victim of crime is still one too many."

The decline in crime severity in 2010 was seen virtually across the country, except for increases in Newfoundland and Labrador, the Northwest Territories and Nunavut.

Police reported nearly 2.1 million Criminal Code incidents last year, down about 77,000 from 2009.

The majority of the decline was attributed to drops in the numbers of property crimes, such as car theft, theft under 5,000, mischief and break-ins.

But there were also fewer homicides, attempted murders, serious assaults and robberies.

There were increases in some areas, however, including sexual assault, firearms crimes, criminal harassment, child pornography and drug offences.

Police reported just over 437,000 violent incidents in 2010, about 7,200 fewer than in the previous year. Violent crimes accounted for just over 20 per cent of offences.

There were 554 homicides in 2010, 56 fewer than in 2009. This 10 per cent drop followed a decade of relative stability.

The national homicide rate of 1.62 for every 100,000 people was the lowest since 1966.

The national decline in homicide was due mainly to a large decrease in British Columbia, where the rate of 1.83 per 100,000 was at an all-time low, although still above the national rate.

The number of attempted murders also declined, to 693 last year from 801 in 2009. This resulted in the lowest rate for this offence in over 30 years.

Police reported more than 22,000 sexual assaults in 2010, up five per cent from 2009 and the first increase since 2005.

As usual, almost 80 per cent of crimes reported to police were non-violent. Theft under $5,000, mischief and break-ins accounted for close to two-thirds of the almost 1.7 million non-violent offences.

Police reported nearly 200,000 break-ins last year, a drop of six per cent.

While there were nearly 93,000 motor vehicles thefts reported in 2010, that was down 15 per cent from 2009.

Drunk driving fell six per cent from 2009, following three consecutive years of increase.

In 2010, police reported over 108,000 drug offences, about half of which were for possession of marijuana. The rate of drug offences increased 10 per cent from 2009, continuing a general upward trend that began in the early 1990s.

Alberta and British Columbia showed the largest declines in crime in 2010. The overall crime rate fell by six per cent in both provinces. The crime severity index also fell in both.

As in previous years, Nunavut and the Northwest Territories continued to report the highest crime severity index levels.

The volume and severity of crime fell or remained stable in 2010 across most all major communities, including the 10 largest cities.

Youth crime was also down. Police reported that nearly 153,000 youth aged 12 to 17 were accused of a crime in 2010, almost 15,000 fewer than the previous year.

Youth crime rates declined for most offences in 2010, including homicide, serious assaults, motor vehicle thefts and break-ins. Robbery was one of the few offences to show an increase for youth in 2010, rising by two per cent.

The index which measures the severity of violent crime by youth showed a four per cent drop between 2009 and 2010, but it was still five per cent higher than in 2000.