The nation's imported vehicle sales dropped 16.9 percent in August to 15,597 units from the same period last year, down for the 17th straight month, the Japan Automobile Importers Association announced Friday.

The drop marks the second-longest period of year-on-year decline since the group started taking statistics in the 1960s, according to the industry association.

The industry body attributed the poor sales in August to the prolonged slump in the nation's economy. The yen's depreciation, which raised the price of imports, was also seen as a factor behind sluggish sales.

"Given the continued sales decline, this year's imported car sales will be around 300,000 units, which is 60,000 units below our initial sales forecast of 360,000 units," a spokesman for the association said.

Sales of imported passenger cars fell 13.2 percent to 14,927 units from a year earlier, while sales of imported trucks plummeted 57.3 percent from the previous year.

However, the spokesman was optimistic, saying the imported car market this month should recover at least to last year's level as sales of new models, such as BMW AG's 3 Series, Volkswagen AG's Golf and Adam Opel AG's Astra, begin to pick up.