Washington ? Consumer prices in August posted their biggest increase in four months, especially hitting the wallets of energy users, clothing shoppers and smokers.

The Consumer Price Index, the government’s most closely watched inflation gauge, rose 0.3 percent in August from the previous month, the Labor Department reported Wednesday.

The advance, the largest since April, came after a tiny, 0.1 percent rise in July.

“I think there is inflation lurking in those hills,” said Richard Yamarone, an economist with Argus Research Corp. “Currently inflation is not yet flashing red but a lighter shade of yellow.”

While the latest reading on inflation was slightly worse than the 0.2 percent increase many analysts were predicting, it did not alarm economists, who believe that the weak economy will make it difficult for companies to raise prices.

“I think businesses will be struggling to maintain sales and the only way they are able to do that is through aggressive pricing: sales, discounts and easy financing deals,” said Mark Zandi, chief economist with Economy.com.

Still, economists said they would be keeping a watchful eye on energy prices, which have risen recently as tensions escalated between the United States and Iraq.

The “core” rate of inflation, which excludes energy and food prices, rose 0.3 percent in August, following a 0.2 percent increase in July.

August’s rise largely reflected a 2.4 percent increase in prices for tobacco and other smoking products. Energy prices last month rose 0.6 percent, following a 0.4 percent increase in July.