WASHINGTON U.S. import prices increased less than expected in September as a strong dollar depressed prices of non-petroleum products, which over time will help to lower domestic inflation.

Import prices edged up 0.1% last month, the Labor Department said on Friday. Data for August was revised higher to show prices climbing 0.6% instead of the previously reported 0.5%.

Economists polled by Reuters had forecast import prices, which exclude tariffs, gaining 0.5%.

In the 12 months through September, import prices dropped 1.7% after falling 2.9% in August. Annual import prices have now declined for eight straight months.

While data this week showed producer and consumer prices rising more than expected in September, underlying inflation remained moderate. That together with rising U.S. Treasury yields and conflict in the Middle East were seen discouraging the Federal Reserve from raising interest rates next month.

Excluding fuels and food, import prices slipped 0.1% after dropping 0.3% in August. These so-called core import prices decreased 1.1% year-on-year in September.

The dollar's strength against the currencies of the United States' main trading partners is dampening imported prices. The dollar has so far this year gained about 1.95% on a trade-weighted basis.

(Reporting by Lucia Mutikani; Editing by Chizu Nomiyama)