The key index of indicators designed to show the current state of the economy rose in September to its highest level in more than five years as firms boosted production and investment, the government said Thursday.

The index of coincident indicators, including industrial output, retail sales and new job offers, climbed to 108.2 from 107.6 in August, against the 2010 base of 100, the Cabinet Office said in a preliminary report.

The figure was the highest since July 2008, before the economy started to wane due to the global financial crisis that began later that year, an official in the office said.

The government left its basic assessment of the coincident index unchanged from the previous month, saying it indicates the economy is "improving."

In September, industrial production increased 1.5 percent from the previous month following a revised 0.9 percent fall in August, buoyed by firm domestic demand for cars and business computers, the Ministry of Economy, Trade and Industry said late last month.

The index of leading indicators, which predicts developments in the coming few months, increased to 109.5 from 106.8, as consumer spending grew ahead of the consumption tax hike set for next April, the official said.

The index of lagging indicators, measuring economic performance in the recent past, rose to 115.1 in September from 114.4 the previous month, the seventh straight monthly increase.

Economists estimate that the economy grew a real annualized 1.4 percent in the July-September quarter, up for the fourth consecutive quarter, following a 3.8 percent expansion in the April-June quarter, a Kyodo News survey showed last week.