Foreclosure rates continued to climb in the first quarter in many parts of the country, casting doubt on the effectiveness of the Obama administration's foreclosure prevention plan, a private foreclosure listing company said Wednesday.

"Industry efforts to date really haven't put a dent yet in the wave of foreclosures," said Rick Sharga, a senior vice president at RealtyTrac, an online foreclosure listing service that releases quarterly reports on foreclosure activity. "Despite the press reports we've had about the many hundreds of thousands of loans that have been modified or worked out or rearranged, the numbers have just kept going up."

Sharga said that new municipalities had appeared on the map during the most recent period as areas with rising foreclosure rates, including Boise, Id., Fayetteville, Ark. and Charlotte.

"It appears we're starting to see the problem spread beyond the primary metropolitan areas into the secondary markets," he said, adding that while foreclosures in Detroit, Mich., were down, rates in Ann Arbour, Lansing and Grand Rapids had risen.

California, Florida, Nevada and Arizona continued to have the highest rates in the country, with Las Vegas coming in as the number one metropolitan area for foreclosures. One in every 22 homes in the city received foreclosure notices during the first quarter.

Sharga said that a major obstacle to loan modifications in these locations was, in his view, the lack of a "safe harbor" provision for servicers in the Obama administration's loan modification plan.

"There's no reason for banks to take the risks of modifying the loans," Sharga said.

Safe harbor clause or no, banks may be reluctant to upset investors, he added.

"If you're a servicer and you unilaterally change something and it irritates your investor, even if you don't get sued you're probably losing your business."

Another problem Sharga said he saw in areas with high foreclosure rates was one of high loan-to-value ratios — figures much greater than the 105% permitted by the administration's plan.

"In most of the markets we're talking about, something like 105% loan-to-value ratio is in most cases a dream," he said. "We're talking about loans that are 150%, 160%, 170% loan-to-value. I don't think the program is really structured in a way that makes those kind of loans reachable."

Sharga said principle reductions would help make loan modifications more effective in the long term.

"There really hasn't been any creativity applied to doing something about principal balance reductions," he said, adding that monthly payment reductions were also not a central part of many loan modifications. "When you see somebody coming in for a loan modification with a $1500 monthly payment leaving with a $1700 monthly payment, you know something's not working."