U.S. fixed mortgage rates this week continued to hover near their all-time lows, which helped keep homebuyer affordability high, said Freddie Mac in its Primary Mortgage Market Survey released Thursday.

The mortgage giant said that 30-year fixed-rate mortgage (FRM) was 3.34 percent in the week ending Jan. 2, down from last week's 3.35 percent, not far from its record low of 3.31 percent.

The 15-year FRM, a popular choice for those looking to refinance, averaged 2.64 percent, down from the previous week's 2. 65 percent, very close to its record low of 2.63 percent.

In addition, the five-year Treasury-indexed hybrid adjustable- rate mortgage (ARM) inched up to 2.71 percent, while the one-year Treasury-indexed ARM was up to 2.57 percent.

"Mortgage rates started the year near record lows which should continue to aid the ongoing housing recovery," said Frank Nothaft, vice president and chief economist of Freddie Mac.

The record low mortgage rates have been acting as an important incentive for house refinancing and buying. With constant improvement this year, the U.S. housing crash is said to have reached the bottom. However, many economists reckon that the market still needs years to recover entirely as the bottom will be prolonged.