Japan's industrial output dropped 1.1 percent in September from a month earlier, the government said in a report on Wednesday.

According to the Ministry of Economy, Trade and Industry (METI), the index of production at factories and mines stood at a preliminary 101.4 against the 2010 base of 100.

This compares to a revised 0.2 percent increase in August on a seasonally adjusted basis.

The index of industrial shipments dropped 3.0 percent to 98.5 and that of inventories was up 2.3 percent at 113.3, the ministry's data showed.

The ministry's basic assessment was kept unchanged from a month earlier and stated that industrial production is "picking up slowly, but shows some signs of weakness."

Looking ahead, manufactures surveyed by METI said they expect output in October to increase 6.0 percent and then edge 0.8 percent lower in November.