Japan's economy grew an annualized real 3.9 percent in the July-September quarter, marking the fourth consecutive quarter of expansion and beating economists' forecasts, the Cabinet Office said in a preliminary report on Monday.

As measured by GDP (gross domestic product) this corresponds to a 0.9 percent growth from the April-June period.

Private consumption rose 1.1 percent on quarter in the July- September period, the Cabinet Office said, following a revised 0.1 percent increase in the previous quarter.

On a nominal basis, GDP climbed an annualized 2.9 percent in the reporting period, which corresponds to a 0.7 percent growth from the April-June period.

The Cabinet Office cited government subsidies for low-emission cars and eco-friendly technology as giving a late boost to consumer spending, prior to the expiration of the subsidies in September.

In addition, domestic demand gained 1.0 percentage, after adding a revised 0.1 in the previous quarter, the report revealed, although public investment decreased 0.6 percent.

Analysts said the pace of the economic growth is likely to slow sharply, or possibly reverse its growth trend in the final quarter of this year, as weakening overseas demand, deflation, waning domestic demand and a strong yen are likely to take their toll on growth.

Following the latest poll of 42 economists and research institutions conducted by the Cabinet Office's Economic Planning Association (COEPA), economists have revised down their forecasts for Japan's economic growth for this fiscal year and fiscal 2011 while projecting prices in fiscal 2011 and 2012 may not rise as much as expected earlier.

GDP is the total value of goods and services produced domestically. Real GDP data are adjusted for price and seasonal variations.