WASHINGTON – A spike in gas prices drove a measure of U.S. consumer costs up in February by the most in more than three years. But outside the gain in fuel costs, inflation was mostly modest.

The consumer price index increased a seasonally adjusted 0.7 percent last month from January, the Labor Department said Friday. It was the biggest monthly rise since June 2009.

Still, three-fourths of the increase in the index reflected a 9.1 percent surge in gas prices. That was also the largest monthly gain since June 2009. Gas prices had fallen in the previous four months. Since last month’s increase gas price have started to decline again.