A container ship is shown at port in Long Beach, California, U.S. July 16, 2018. REUTERS/Mike Blake

WASHINGTON (Reuters) - U.S. import prices increased more than expected in October, boosted by a surge in petroleum and food prices, but underlying imported inflation pressures remained tame amid a strong dollar.

The Labor Department said on Thursday import prices rose 0.5 percent last month after a downwardly revised 0.2 percent gain in September.

Economists polled by Reuters had forecast import prices gaining 0.1 percent in October after a previously reported 0.5 percent increase in September.

In the 12 months through October, import prices advanced 3.5 percent after rising 3.1 percent in September.

Last month, prices for imported fuels and lubricants jumped 3.3 percent after rising 0.7 percent in September. Food prices surged 2.2 percent in October after rising 2.0 percent in the prior month.

Excluding fuels and food, import prices fell 0.1 percent last month after declining by the same margin in September.

The so-called core import prices advanced 0.7 percent in the 12 months through October. The monthly drop in core import prices likely reflects the strong dollar, which has gained about 8.1 percent this year against the currencies of the United States’ main trade partners.

The report also showed export prices rose 0.4 percent in October after being unchanged in September. Prices for agricultural products fell for second straight month. Export prices increased 3.1 percent on a year-on-year basis in October after rising 2.7 percent in September.