Mortgage applications more than doubled last week as government bailouts led to sinking interest rates that made refinancing especially attractive, the Mortgage Bankers Association reported this week.

The Market Composite Index — the organization’s measure of mortgage loan application volume — surged 112.1 percent on a seasonally adjusted basis from the week earlier.

On an unadjusted basis, the index increased 51.4 percent from the previous week, down 21.9 percent from a year earlier. Results included an adjustment to account for the Thanksgiving holiday.

Rates plummeted following the Fed’s announcement that it would buy debt and mortgage-backed securities from mortgage finance companies Fannie Mae and Freddie Mac.

The Mortgage Bankers Association said 30-year fixed-rate mortgages fell to 5.47 percent this week, down from 5.99 percent last week.

Rates on 15-year fixed-rate mortgages fell to 5.13 percent from 5.78 percent.

The report’s Refinance Index increased 203.3 percent to 3802.8 from the previous week, and the seasonally adjusted Purchase Index increased 37.4 percent.