Average long-term U.S. mortgage rates declined this week, approaching historically low levels with the spring home-buying season underway.

Mortgage giant Freddie Mac said Thursday the national average for a 30-year fixed-rate mortgage slipped to 3.66 percent from 3.70 percent last week.

The average rate for a 15-year mortgage, popular with homeowners who refinance, fell to 2.93 percent from 2.98 percent last week.

A year ago, the average 30-year mortgage rate was 4.34 percent and the 15-year rate was 3.38 percent.

Mortgage rates have remained low even though the Federal Reserve in October ended its monthly bond purchases, designed to hold down long-term rates. The Fed signaled recently that it’s still not ready to start raising short-term rates, after keeping them near zero for over six years.

Tepid job growth in March, as shown in a government report last Friday, could make the Fed less likely to begin raising rates in June, as some have been anticipating. The Fed could decide that the economy still needs the benefit of low borrowing costs to generate healthy growth.

The Labor Department report indicated that a weakening U.S. economy spilled into the job market last month as employers added just 126,000 jobs — the fewest since December 2013.

Fed officials disagreed widely when they met last month on when they would be ready to lift rates. Minutes of the March 17-18 meeting released Wednesday show that several policymakers predicted a rate hike in June, while others concerned about low inflation didn’t think a rate hike would be warranted until later this year. Still others said the economy wouldn’t be strong enough for an increase until 2016.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country at the beginning of each week. The average doesn’t include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage was 0.6 point, unchanged from last week. The fee for a 15-year mortgage also remained at 0.6 point.

The average rate on a five-year adjustable-rate mortgage fell to 2.83 percent from 2.92 percent. The fee stayed at 0.5 point.

For a one-year ARM, the average rate was unchanged at 2.46 percent. The fee remained at 0.4 point.

(AP)