Japan posted its biggest monthly trade deficit in January, due to a combination of rising energy prices and weak exports.

The Finance Ministry said on Thursday the deficit reached almost 3.5 trillion yen, or more than 26 billion dollars.

The trade balance has now shown a deficit for 18 straight months. The amount was the most since comparable data became available in 1979.

Imports swelled 17.8 percent in yen terms from a year earlier to 75 billion dollars.

But exports increased by just 3.5 percent to 49 billion dollars.

Exports to China, Japan's biggest trade partner, fell by 17.1 percent. That was mainly because Chinese business activity ground to a halt during the Lunar New Year holidays.