Japan's trade deficit nearly doubled in October, as growth in imports outpaced robust increases in exports to the U.S. and China, the Finance Ministry reported Wednesday.

A weakening in the Japanese yen over the past year has helped exports, but it has also increased the cost in yen terms for imports, especially of oil and natural gas to help offset the loss of generation capacity from nuclear plants idled after meltdowns in 2011 at the Fukushima Dai-Ichi nuclear power plant.

A 68 percent increase in costs for imported crude oil in October helped push the trade deficit up 96 percent over a year earlier to 1.09 trillion yen ($10.9 billion), the preliminary customs data showed. Imports surged 26 percent year-on-year to 7.2 trillion yen ($72 billion), while exports climbed nearly 19 percent to 6.1 trillion yen ($61 billion).

It was the 16th straight month of deficits, which also reflect lackluster demand for exports thanks to a slowdown in growth in China and other developing economies.

In yen terms, Japan's vehicle exports jumped 24 percent over a year earlier. Exports of chemicals, machinery and electronics also rose at a double-digit pace. But the offshoring of much of Japan's manufacturing is increasing the costs for industrial components such as semiconductors and optical lenses, further eroding net export growth. Imports of electronics rose 28 percent.

The United States remained Japan's biggest export market, with shipments rising 26 percent from the year before to 1.16 trillion yen ($11.6 billion), while exports to China climbed 21 percent to 1.15 trillion yen ($11.5 billion).