U.S. import prices rose faster than expected in August, recording their largest increase in four months on higher petroleum and food costs, according to a government report on Wednesday that hinted at an uptick in imported inflation.

Import prices increased 0.6 percent after rising by a revised 0.1 percent in July, the Labor Department said.

Analysts polled by Reuters had forecast import prices rising 0.3 percent last month from a previously reported 0.2 percent gain in July.

In the 12 months to August, import prices increased 4.1 percent, the smallest advance since November.

August's monthly rise reflected a 2.1 percent rise in the price of imported petroleum and petroleum products, the largest since April, after a 0.9 percent increase in July. Excluding petroleum, import prices rose 0.2 percent, reversing the prior month's 0.2 percent decline.

Prices of imported foods jumped 2.2 percent from a 0.1 percent rise in July. There were also increases in prices for industrial supplies and materials.

The Labor Department report showed export prices rebounded 0.8 percent last month after slipping 0.2 percent in July. Export prices were boosted by a 4.3 percent jump in food prices, the biggest rise in 14 months.

Analysts had expected export prices to gain 0.2 percent.

Compared to August last year, export prices rose 4.1 percent.

Separately, a gauge of manufacturing in New York State unexpectedly fell to its lowest level in more than a year in September, the New York Federal Reserve said in a report Wednesday.

The New York Fed's "Empire State" general business conditions index slipped to 4.14 in September from 7.10 in August.

September's reading marked the lowest since July 2009.

Economists polled by Reuters had expected a reading of 8.0 for September.

Employment gauges showed continued improvement. The index for the number of employees rose to 14.93 in September from 14.29 in August. The average employee workweek index increased to 7.46 from 7.14.

The index of business conditions six months ahead fell to 31.34 in September from 35.71 in August.

The survey of manufacturing plants in the state is one of the earliest monthly guideposts to U.S. factory conditions.