Mortgage demand jumped to a five-month peak last week, with applications to buy homes up from 13-year lows set in the wake of buyer tax credits while refinance loans hit the highest level since May 2009.

Mortgage purchase applications rose 7.3 percent after sinking five weeks in payback for steamy demand before the April 30 deadline for $8,000 in tax credits, the Mortgage Bankers Association said on Wednesday.

Borrowing costs hovering near record lows sparked a rush last week to cut costs on existing loans, driving the refinance applications index up 21.1 percent to the highest level in 13 months.

Total home loan applications, up 17.7 percent in the week on a seasonally adjusted basis, have not been higher since mid-December, according to the industry group.

It is premature to determine that the tax credit hangover has fully played out and the U.S. housing market is crossing the threshold into recovery.

While it is clear that purchase applications in May dropped sharply as a result of the tax credit induced increase in applications in April, it is unclear whether we are seeing the beginnings of a rebound now, Michael Fratantoni, MBA's vice president of research and economics, said in a statement.

In a sign of ongoing stress in the housing market, builder sentiment sank this month as the end of tax incentives clouded prospects for future sales, the National Association of Home Builders said on Tuesday.

Requests for refinancing continue to overshadow purchases.

About 3 of every four mortgage applications -- 74.8 percent -- was for a refinancing last week. That was the highest share since mid-December.

Average 30-year home loan rates climbed 1 basis point but stayed low historically at 4.82 percent.

Long-term mortgage rates have fallen as low as 4.61 percent in March 2009, according to the MBA, but remain about 1/2 percentage point below the recent high of 5.31 percent in April.