TORONTO -- Ontario's social assistance costs ballooned under the previous Liberal government but the system failed to help recipients become self-reliant, the province's auditor general said Wednesday.

In her annual report, Bonnie Lysyk said the number of Ontario Works cases has increased by almost 25 per cent since 2009, hiking costs up more than 55 per cent to nearly $3 billion.

At the same time, the program only helped 10 to 13 per cent of recipients find work in the last five years, Lysyk said.

"A central finding in almost all of the audits this year was that spending of public monies did not consistently result in the cost-effective achievement of anticipated program benefits, or the proactive addressing of program risks," she said.

"We also found that, contrary to what people would expect, the government did not always take all steps necessary to ensure that programs are providing financial assistance only to eligible people."

Since the Progressive Conservatives formed a majority government in June, the auditor's report deals with the actions of the previous Liberal regime in 15 value-for-money audits.

In scrutinizing the province's transit agency, Metrolinx, Lysyk found the previous minister of transportation improperly influenced the selection of two GO Transit train stations, overriding the agency's own analysis that suggested the stations should not be built for at least a decade.

She also found that light-rail projects planned for the Greater Toronto and Hamilton areas incurred roughly $436 million in unnecessary costs since 2009 because of problems in the transit-planning process and how Metrolinx carries out its responsibilities.

"After certain projects were announced or agreed on, the provincial and municipal governments changed their decisions on what to build and when to build, even though significant investments had already been made," Lysyk said.

She cited the City of Toronto's reversal on a transit project in the east-end area of Scarborough -- changes that occurred while Premier Doug Ford served as a city councillor and his late brother, Rob Ford, was mayor.

The report also includes a review of government advertising, which found the Liberals spent $62.5 million on advertising last year -- the most in more than a decade. What's more, the auditor said, 30 per cent of those ads would not have been approved under more stringent rules previously in place.

Another section of the auditor's report found the government could save money by hiring full-time IT staff instead of relying on consultants for long-term contracts.

In one case, a consultant was signed to a 14-month, $210,000 contract to develop a software application in 2014. But Lysyk found that contract was extended three times over as many years, for a total cost of more than $900,000. She said the average cost of permanent IT staff suggests the work could have been done internally for 40 per cent less.

Peter Graefe, a political science professor at McMaster University, said the report will give the governing Tories more ammunition to criticize their predecessors.

"Usually this is one of the worst days of the year for government," he said. "But for a new government, particularly replacing one that's been there for 15 years, it's like candy, in the sense that it allows them to further browbeat a Liberal party that is in very weak shape provincially."

It also gives them excuses to go and make changes in a variety of areas, Graefe said, because "they have this report where the auditor general says that there's been something that hasn't been done right in area X and so under the pretext of responding to that problem they presumably do a number of other changes."

The auditor's scrutiny of the Ontario Works program will likely be of interest to the government, for example, he said, noting that it could help the Tories sell recently revealed changes to social assistance.

The Progressive Conservatives laid out a broad vision for social assistance reform last month, promising to cut red tape and encourage people to get back in the job market.

People receiving disability support from the Ontario government will be able to keep more of the money they earn as part of the changes, but critics have said it will be harder to qualify for help.

Interim Liberal leader John Fraser has said he was worried the auditor's report would be used by the Tories to justify cuts.

The Tory government has already called a commission of inquiry and a financial review to examine the Liberals' spending, as well as a special committee to look into the party's Fair Hydro Plan.

Those measures led Doug Ford's government to declare that the province's deficit is far greater than originally believed, and to call for provincewide belt-tightening.

The Ford government has also put an end to a longtime dispute with the auditor general over accounting methods for two pension plans and the Fair Hydro Plan, saying the province would adopt Lysyk's approach.