Japanese vehicle production in 2011 dropped 12.8 percent from a year earlier and vehicle exports fell 7.8 percent, marking the first drop in two years, as the March 11 disasters forced manufacturers to shutter operations, which disrupted key supply chains, an industry group said Tuesday.

In 2011, 8.39 million vehicles were produced, down by 1.23 million units or 12.8 percent from a year earlier, the Japan Automobile Manufacturers Association said in their latest report.

Car production declined 13.9 percent to 7,158,525 units and truck output dropped 6.1 percent to 1,136,020 units. Bus output, meanwhile, stood at 104,109 units, down 4.8 percent in the recording period, the association said.

The association added that 4.46 million vehicles were exported in the recording year, a drop of 7.8 percent from a year earlier, also falling for the first time in two years.

For the month of December, however, automobile production rose 13.4 percent from a year ago to 848,208 units, marking the third straight month of increase and accelerating away from the 4.5 percent rise logged in November, the association said.

But exports in the recording month slumped 2.1 percent to 457, 464 units, marking the first decline in five months, as manufacturers came under a pressure from a strong yen versus its major counterparts and from debt turbulence in the crisis-hit eurozone.

Exports of cars retreated 8.1 percent to 3,929,904 units, while those of trucks declined 5.9 percent to 423,767 units. Bus exports, meanwhile, fell 4.4 percent to 110,742 units, the association's figures showed.

Japanese carmakers' exports to the United States skidded down 6. 8 percent to about 1.43 million units, in the recording month, while exports to Asia shed 0.7 percent totaling 572,000 units.

Vehicles made by Toyota Motor Corp., Japan's top-automaker, declined 15.9 percent to 2.76 million units, with exports falling 10.1 percent year-on-year to 1.57 million units, the Japan Automobile Manufacturers Association said.