Car sales in Japan declined by 9.1% year-on-year in August as the market was weighed down by sales tax increases.

Official data put car sales in August at 333,471 units. The decline was expected because the timing of the tax increase in April brought car sales forward earlier in the year. Sales rose for seven straight months before the April 1 tax increase.

However, some analysts are concerned that continuing weak demand for cars in Japan might also reflect an underlying slowdown in the pace of Japan's economic growth.

"Looking at current dealer orders, it's difficult to see sales rising even after September," said Yoshitaka Hayashi, a director at the Japan Automobile Dealers Association speaking to Bloomberg.

Sales had been expected to rebound in the July-September quarter when many Japanese workers typically receive a bonus, Hayashi told the news agency.

Deliveries of minicars also fell 15.1% to 126,865 vehicles, according to the Japan Mini Vehicle Association.