Dec. 6 (Bloomberg) -- The number of Americans who fell behind on their mortgage payments rose to a 20-year high in the third quarter as borrowers were unable to refinance or sell their homes.

The share of all home loans with payments more than 30 days late, including prime and fixed-rate loans, rose to a seasonally adjusted 5.59 percent, the highest since 1986, the Mortgage Bankers Association said in a report today. New foreclosures hit an all-time high for a second consecutive quarter.

The surge in foreclosures is expanding the inventory of unsold homes and contributing to the decline in housing demand. Sales of new and previously owned homes probably will drop to 5.09 million next year, 32 percent below the 2005 peak of 7.46 million, according to Frank Nothaft, chief economist of Freddie Mac, the second largest U.S. mortgage buyer. About 40 percent of lenders have increased standards for their most creditworthy borrowers, according to a Federal Reserve study in October.