Los Angeles' much-debated red light camera program has bypassed some of the city's most dangerous intersections, cost more than $2.5 million over the last two years and failed to adequately demonstrate an improvement in safety, according to an audit due to be released Wednesday by City Controller Wendy Greuel.

The study, the first independent assessment of a program that catches tens of thousands of violators annually, comes as officials are hoping to add to the city's 32 photo-enforced intersections. Details of the audit findings are scheduled to be released at a morning news conference with Los Angeles Police Chief Charlie Beck and City Councilman Dennis Zine.

Greuel's office noted in an advisory that the decade-old camera program was supposed to reduce accidents at the highest-risk intersections. But auditors found that some of the most accident-prone corners were passed over -- partly for political reasons, such as ensuring that at least one camera system was placed in each of the 15 City Council districts.

Only half of the intersections equipped with cameras showed a reduction in accidents, according to Greuel's office.

LAPD officials, who have insisted that the cameras have improved safety and reduced fatalities at those intersections, were not immediately available for comment.

But program operators at the LAPD and city transportation department have been unable to conclusively document safety improvements, the audit found. A more comprehensive means of evaluating the effectiveness of cameras is needed, the report says.