Mortgage researcher RealtyTrac said Thursday that U.S. foreclosure activity rose 6 percent in February over January and 30 percent over February 2008.

In spite of moratoriums on foreclosures announced by several large banks, Thursday's report showed one in every 440 U.S. housing units were issued foreclosure filings in the month.

Nevada topped the list with one in every 70 housing units -- amounting to 15,783 homes -- receiving a filing in the month, a 9 percent gain over January. In Arizona, one in 147 housing units received filings. In California, one in every 165 housing units were served notices.

In total numbers, California topped the list with 80,775 housing units served.

Among cities with a population of 200,000 or more, Sun Belt cities have been hardest hit, the report said.

In Las Vegas, one in 60 housing units were served, the highest rate in the country. Cape Coral-Fort Myers, Fla., ranked second with one in every 65 housing units served. Stockton, Calif., was third on the list with one in every 67 homes receiving fillings in the month.

Nebraska, among states, had the lowest rate of foreclosure filings with one in every 60,062 housing units served, the report said.