Mortgage rates have surged over the past week, making the purchase of a new home even less attractive in the already weak housing market.Government-backed mortgage giant Freddie Mac ( FRE) reported Thursday that fixed-rate mortgages have reached their highest level in nearly a year. The rise in mortgage rates comes as banks continued to fear that the cash-strapped lender and its counterpart, Fannie Mae ( FNM), will slow their purchase of loans. Freddie said in an SEC filing last week that it may even sell some mortgage securities to shore up capital levels. Weaker demand leads to higher interest rates, and all types of mortgages have been driven upward over the past week. Certain rates move in tandem with Treasury notes, which have also been pushed higher over the past week. The yield on the 10-year Treasury bond was at 4.148% by noon on Thursday, up from 4.038% a week earlier. Freddie's chief economist Frank Nothaft also noted that large jumps in consumer prices, a 4.8% drop in housing prices, and a decline in new-home construction also contributed to the higher rates. The average rate for a 30-year fixed mortgage climbed to 6.63% from 6.26% just a week earlier, according to Freddie. The average upfront payment was six-tenths of a percent. The 15-year fixed rate rose to 6.18% from 5.78% with the same upfront payment. Five-year adjustable-rate mortgages that are hybrids indexed to Treasurys averaged 6.16% from 5.8% a week ago. The average upfront payment was seven-tenths of a point. Shorter term one-year ARMs averaged 5.49% with an average payment of half a point, up from 5.1%. Consumers can check the most competitive rates available locally by entering their ZIP codes at BankingMyWay.com.