The number of Americans filing mortgage applications shot up 6.2% for the week ending Dec. 7, an industry trade group said.

The surge included 8% growth in the refinancing index and a 1% increase in home purchase applications.

"Continued uncertainty due to the lack of resolution regarding the fiscal cliff led interest rates lower last week, with mortgage rates reaching a new low in our survey," said Mike Fratantoni, MBA’s vice president of economic research. 

The refinance share of all mortgage activity edged up to 84%, compared to 82% a week earlier.  

More Americans applied for loans as the 30-year, fixed-rate conforming mortgage fell to its lowest recorded level of 3.47%, down from 3.52%.

The 30-year, FRM jumbo loan also declined to 3.77% from 3.79%.

In addition, the average 30-year, FRM backed by the FHA fell to 3.32%, down from 3.34%. The average 15-year, FRM fell to 2.85%, which is its lowest point in survey history, and down from 2.86%.

The 5/1 ARM increased to 2.63% from 2.62%.