Owners-equivalent rent, one of the categories designed to track rental prices, also rose 0.2 percent after rising 0.3 percent in July. Mounting foreclosures are reducing homeownership while boosting demand for rental housing.

The core gauge rose after a 0.2 percent increase in July. Economists had forecast a 0.2 percent August gain, according to the survey median.

Overall consumer prices increased 3.8 percent in the 12 months ended August, matching the year-over-year gain the prior month. The core CPI rose 2 percent from August 2010, more than the median forecast of a 1.9 percent increase and the most since November 2008.

Core Inflation

The Fed's informal target range for longer-term core inflation is 1.7 percent to 2 percent as measured by a Commerce Department gauge tied to consumer spending.

Today's report showed energy costs increased 1.2 percent from a month earlier. Gasoline prices climbed 1.9 percent and were up 32 percent from a year earlier.

The consumer price report follows Bernanke's comments last week to the Economic Club of Minnesota that central bank officials expected inflation to slow as prices for oil and other commodities ease.

"We see little indication that the higher rate of inflation experienced so far this year has become ingrained in the economy," Bernanke said. "Inflation is expected to moderate in the coming quarters," he said, citing the waning of "transitory" influences like high fuel prices and global supply disruptions linked to Japan's March earthquake and tsunami.

Food costs rose 0.5 percent, driven by higher dairy, meats, fruits and vegetable prices.

The cost of medical care rose 0.2 percent. Costs of passenger cars were unchanged, while used vehicle prices increased 0.9 percent. Apparel costs climbed 1.1 percent, the most since March.