Mortgage rates in the U.S., already increasing at the fastest pace in a decade, are poised to rise even further after Federal Reserve Chairman Ben S. Bernanke said the central bank is ready to slow its purchases of Treasuries and bonds backed by housing loans.

Yields on Fannie Mae's 3.5 percent, 30-year securities have soared 0.39 percentage point in the past two days to a 19-month high of 3.11 percent. The average rate on new loans packaged into such bonds rose last week to 3.98 percent, the sixth straight increase, from 3.35 percent at the start of May, Freddie Mac surveys show.