(Adds reaction from prime minister's office, opposition)
By David Ljunggren
OTTAWA, June 9 (Reuters) - Members of Canada's Senate improperly spent almost C$1 million ($810,000) in just two years, according to a report released on Tuesday that will put pressure on Conservative Prime Minister Stephen Harper ahead of October's general election.
After receiving the report from Auditor General Michael Ferguson, the Senate last week referred the cases of two sitting and seven former senators to police for criminal investigation.
The watchdog's report follows a spending scandal involving senators, who are appointed to Parliament's upper chamber by the prime minister of the day and serve indefinitely until age 75.
The 105-member Senate, officially charged with reviewing legislation passed by the lower house, has historically been criticized as a dumping ground for political operators. The recent scandal has pushed it deeper into disrepute.
Ferguson's investigation uncovered C$992,663 in irregular spending and expense claims made by 30 current and former senators. Eight of those senators were appointed by Harper, who is trying to pull off a rare fourth consecutive election victory in October.
Opposition legislators say the scandal makes a mockery of the promise Harper made when he took power in 2006 to increase accountability and clean up the Senate. Polls show he will struggle to win another majority.
Harper insists the scandal has nothing to do with him and those found guilty should be punished. The official opposition New Democrats, who have never held power federally and therefore have never appointed a senator, say he is deeply implicated.
"The responsibility for this scandal continues to go back to the prime minister of this country who promised reform ... We deserve better," senior party legislator Charlie Angus told reporters. The New Democrats want to abolish the Senate.
Asked whether the report could hurt Harper's election chances, Harper spokeswoman Catherine Loubier said any abuse of taxpayer dollars was unacceptable.
"(We are) focused on what matters to Canadians - helping families make ends meet by lowering taxes, protecting and creating jobs and keeping our country safe," she said.
Ferguson, who looked at the period from April 2011 to March 2013, said he was struck by "the depth to which a number of senators simply felt that they didn't have to account for ... their spending." His audit cost C$23.5 million.
Two of the 30 senators in question are Leo Housakos, speaker of the chamber, and Claude Carignan, government leader in the Senate.
Both are Harper appointees, as is Senator Mike Duffy, who is on trial facing charges of bribery and improper spending. Ferguson's report did not cover Duffy.
Harper's chief of staff resigned in May 2013 after it emerged he had secretly given Duffy a C$90,000 check to help cover expenses Duffy was deemed to have claimed improperly.
One of the two sitting senators whose cases will be examined by police is Harper appointee Pierre-Hugues Boisvenu. The other, Colin Kenny, was named by the Liberals when they held power.
Housakos told reporters he accepted Ferguson's recommendation that more spending controls be imposed. He said the chamber has started tightening rules.
$1=$1.23 Canadian Editing by Peter Galloway and Cynthia Osterman