WASHINGTON — U.S. consumer prices increased 0.4% in February, the biggest increase in six months, led by a sharp jump in gasoline prices.

The Labor Department said today that the February advance in its consumer price index followed a 0.3% rise in January and was the largest advance since a similar 0.4% increase in August.

Over half of the increase came from a second monthly surge in gasoline prices, which rose 6.4% after a 7.4% jump in January. Gasoline costs have been climbing since December, reflecting rising costs of crude oil.

Consumer prices are up 1.7% over the past year, a still moderate performance for inflation which is running below the Federal Reserve’s 2% target for price increases. Core inflation, which excludes volatile food and energy, was up just 0.1% in February and 1.3% for the past 12 months.