U.S. export prices fell for the sixth straight month in August while prices for non-petroleum imports fell, signs of slack in global demand and in the domestic economy.

Export prices fell 0.5 percent during the month, the Labor Department said on Thursday.

Much of the drop was due to a sharp decline in prices for exports from the volatile farm sector, but non-agricultural exports declined as well and have fallen in every month since March.

The decline comes despite some recent signs that the European economy is getting back into gear following a recent recession.

Economists polled by Reuters had expected export prices to rise 0.1 percent last month.

Import prices also confounded analysts during the month, remaining flat. Economists in the Reuters poll had expected a 0.4 percent gain.

Import prices have trended lower over the last year, with the decline driven largely by the non-oil component. This pattern was also evident in August, with fuel import prices up 0.5 percent and non-petroleum prices down 0.2 percent.

Non-petroleum import prices have now declined every month since February, a sign that foreign producers have little leverage to raise prices for consumers.

This has helped keep the pace of inflation very low over the last year - so low that some U.S. Federal Reserve officials have expressed concern. Fed Chairman Ben Bernanke has warned that extremely low inflation raises the risk that the economy could fall into a vicious spiral of falling prices and wages known as deflation.