WASHINGTON (Reuters) - U.S. import prices rose in September, with prices outside petroleum products posting strong gains, suggesting a weakening dollar was lifting imported inflation. The Labor Department said on Thursday import prices increased 0.3% last month. Data for August was revised up to show import prices increasing 1.0% instead of 0.9% as previously reported. Economists polled by Reuters had forecast import prices, which exclude tariffs, rising 0.3% in September. In the 12 months through September, import prices fell 1.1% after decreasing 1.4% in August. Petroleum prices fell 4.2% last month. Excluding petroleum, import prices increased 0.7%. That followed a 0.8% jump in August. The dollar declined 5.6% against the currencies of the United States’ main trade partners between April and September. The strong rise in ex-petroleum import prices together with a strong increase in producer prices in September suggests that a recent slowdown in consumer inflation was unlikely to translate into falling prices. Imported food prices increased 0.8% last month. The cost of goods imported from China were unchanged after edging up 0.1% in August. Prices were flat year-on-year in September. Last month, prices for imported capital goods ticked up 0.1%. The cost of imported motor vehicles rose 0.2%. Prices for consumer goods excluding autos gained 0.1%. The report also showed export prices rose 0.6% in September, lifted by gain in nonagricultural and agricultural goods. That followed a 0.5% increase in August. Export prices fell 1.8% on a year-on-year basis in September after declining 2.7% in August.