Growing problems in commercial real estate won’t set off a new banking crisis, Treasury Secretary Timothy Geithner said Friday.

“That’s a problem the economy can manage through even though it’s going to be still exceptionally difficult,” he said in response to a question at the Economic Club of Chicago.

“You can say now with confidence that the financial system is stable, the economy is stabilized,” Geithner said, noting the report this week that GDP grew at an annual rate of 3.5 percent in the third quarter.

Geithner’s assurances about commercial real estate, reminiscent of similar remarks made by federal officials when the subprime crisis began to evolve, came as analysts are concerned that banks are not building sufficient reserves for potential losses in the sector.

The pace at which U.S. commercial banks are adding to their loan loss reserves has slowed this year, even though loans continue to go bad at a brisk pace, according to article in Fortune.

The disconnect is particularly acute in commercial real estate, the magazine said, where lenders are facing a wave of defaults on commercial mortgages and construction loans made during the recent boom.

The trend comes as ill-defined or inconsistently applied rules for valuing securities and handling loan modifications can make it hard for analysts to determine how healthy banks really are, the article said. The rebound in banking could prove to be illusory if the losses overtake the industry, analysts warned.

“The credibility of the banking system could take another step back,” Paul Miller, an analyst at FBR Capital Markets, told Fortune. “Everyone is expecting we’ve seen the peak in losses, but it’s impossible to know for sure because you can’t get an apples-to-apples comparison.”

Nonperforming and restructured assets grew six times as fast as loan reserves over the past year, Fortune reported, based on estimates by analysts at Keefe Bruyette & Woods. This pattern suggests “the banks are not ahead of the curve in providing for troubled loans,” the analysts wrote in a recent report.

Prices on apartment, industrial, office, and warehouse properties dropped 33 percent over the past year, according to the Moody’s/REAL commercial property price index.

Real estate research firm Foresight Analytics estimates banks should have booked losses on around $110 billion of defaulted commercial real estate and construction loans, Fortune reported, but so far they have accounted for only about a third of those cases.

So banks could be carrying a backlog of some $70 billion in defaulted but unreserved loans heading into the worst phase of a down cycle in commercial real estate, as the bulk of bubble-era loans come due between 2010 and 2012, Fortune said.

This time, the brunt of the losses would be borne by regional and community banks, rather than the big banks benefiting from the recent bailout. Banks with assets between $100 million and $10 billion have nearly $900 billion of commercial real estate exposure, Fortune said.

“Right now, we’re closer to the beginning of this problem than the end,” Matthew Anderson, a partner at Oakland, California-based Foresight Analytics told Fortune.